Last attempt at making A10 work was done here: GitHub - jernejsk/LibreELEC.tv at mele
There are no images made from these sources anymore. I don't recall what was wrong, but it wasn't much useful afaik.
First thing is to build image, assess what works and what not and start fixing things. If you're not familiar with Linux and U-Boot (if boot doesn't work), you have a long road ahead.
everything working except that pvr.iptvsimple CANNOT be installed
Currently nightly image has no real benefit over stable, so if you need addons, I highly suggest stable image from LE download page.
It is written that 9.97.1 should be able to upgrade automatically, but that didn't work for me, so I have flashed again with final 10.0 LE. But I wonder if it really has to be able to update on our boards, or only manual is our way?
Automatic updates are turned on with a slight delay (few days). Allwinner platform is not treated any differently with automatic updates.
Images are linked on download page: Allwinner – LibreELEC
levitsky86 I would not use 11 nightly images just yet. A lot of updates went in and yes, addons need to be rebuild. I strongly suggest you use latest LE10 RC image.
Default governor is schedutil - this should good enough for most needs. Consider also that you're comparing two completely different ecosystems. If you would check Android serial console, you'll notice that kernel often disables cores due to too high temperature. It's complete chaos there regarding temperature control. It's also possible that temperature sensor is not completely correctly calibrated on LE. You can check that with thermo gun, if you have one.
unmesh Thanks, so now I know owners of all 3 wifi variants. After LE10 is released, I'll start preparing wifi support (with mainline drivers).
chalesy Your board could be supported, but first somebody (most likely you since others probably don't have interest in your box) have to submit board support patches to U-Boot and Linux. As soon as there is general consensus that they're ok (that can be before they're actually merged), I can add support for it here. If you want help with this, I can coach you, since I'm reviewer for Allwinner Linux patches and U-Boot contributor.
Please understand that we have this procedure in place in order to be able to drop patches in not so far future. Nobody likes to maintain patches forever.
There is, but you would have to power up wifi first via DT (overlay or editing). It's easier to crack it open. However, if you don't feel like doing it, that's ok.
In my case, the problem may not be related to ffmpeg. I just restarted the system and then I didn't do anything.
This is probably something else, then.
I was surprised that the serial console log contains only the system boot and then nothing.
Printing on serial in theory slows down boot, if only for a second or less.
Would it be possible to make some debug image that would write in detail to the serial console?
no need, just remove quiet from extlinux.conf. If you want terminal on serial, also add systemd.debug-shell=ttyS0
That message can be ignored. First time driver is probed, not all dependencies are loaded, so it fails with above message. Second time it succeeds. If it wouldn't, you wouldn't have anything on screen.
I never experienced system freeze on OPi3. However, I did experience occasional Kodi crash on it. Other H6 boards/box that I have work fine. I tried to debug this problem several times, but I couldn't find anything useful, except that it crashes in ffmpeg during video decoding. This is elusive long standing bug on OPi3, which will obviously remain for time being. I'll take a look again in the future, but no promises.
My problem could be very well related to yours. It could be due to too high memory clock or insufficient voltage or even due to some driver bug. In short, it's very hard to debug that.
Last question, can I buy you a beer?
Thanks, but currently I don't have any "buy beer" link ready. You can always buy beer LE team 
gkatev CEC is probably something that will never work in all cases. That being said, H3 uses SW implementation which should work with majority of TVs. I forgot details, but IIRC address f.f.f.f means CEC is not supported. Make sure it's enabled on your TV (common issue). Another possible reason would be AVR (if you have it). Try connecting directly first. At the end, you can also try different HDMI cable. Some cables may not have CEC line connected.
okabekudo It could be voltage issue. That can be easily checked with voltmeter. Note that your box is not supported by Linux nor U-Boot and I don't have it, so you're pretty much on your own to figure this out. Strange issues are not uncommon for TV boxes due to cost optimizations. That's the main reason why Allwinner port of LE supports mostly SBCs and only 3 TV boxes which we have and test images on them.
U-Boot development process is similar to Linux, which excludes any fancy stuff like issues on github. In fact, U-Boot github page is unofficial and just clone of official gitlab portal. Issues should be reported on mailing list with CCing respective maintainers.
Uphantom88 USB drive is not supported boot media. Only SD card, eMMC, NAND and SPI NOR. LE supports only SD card and eMMC. You can open box up and check which storage is used. If it doesn't have SD card nor eMMC, you can forget doing anything with it. Even with eMMC only, it would be pretty tedious to boot LE over FEL (USB protocol used for "rescue"). As I said before, there is a reason why only few TV boxes are supported.
One last question, I've read about a device tree file it's needed to make things work, but if I'm not mistaken, this nightly version comes with that included? I've just tested and the box boots just fine from LE, no SD card needed.
Without device tree file box wouldn't even boot, so it's all good 
TX6 has Allwinner H6 SoC. "installtointernal" is Amlogic thing. Allwinner port has "install2emmc".
I do see that we have rom for a10 & a20 devices
Not really, support was dropped, so only unmaintained images exist.
In short, no.
Long answer: A23, as you said, is very similar to A20, so it has same issues. No HDMI audio (patches exist, but have some issues), no HEVC support (if you need it at all), limited memory bandwidth, HW deinterlacing would be hard to implement. I also don't have any board with A23.
If someone steps up as maintainer and kernel developer (for missing features and fixing bugs), we can (re)introduce support. However, it's hard to find such people.
That's about 1.43 seconds per minute drift, which is about right for imprecise RC oscillator. Only thing we can do about it, is to run NTP sync right after resume, as you suggested. But to be honest, I'm not knowledgeable enough about systemd services to fix that right away. I'll check few sources...
ElwoodSC If I understand correctly, clock difference is the same as the amount of time spent in suspend state? If that's true, then RTC is accidentally stopped when transitioning to suspend state.
Note that Tanix TX6 doesn't have dedicated RTC oscillator on board. It uses internal RC oscillator, which has terrible precision. Drift can be 0.5 second or more per minute.
Wait on network is used only at boot if I'm not mistaken. It's meant to wait on network to become available, so all addons, which depend on network availability, can work. If anything, you can try with longer delay, I wouldn't disable it in your case, since you're using PVR backends and SMB.
Anyway, please try test image anyway. If nothing else, it should lower power consumption, since it disables Ethernet PHY in suspend.
