I'm an hobbist and a bad developer, but I'll try. I'll try also to buy this board.
Chat to Da and he'll probably just send you one. Worst case feel free to acquire one and expense to LE via OpenCollective. We can always discuss that process more in Slack if needed.
LibreELEC is an intentionally simple distro but we should support all the normal bash scripting commands because we use the same things within the distro. Note that we use busybox for lots of things which can reduce command options. The full /usr/bin/vcgencmd binary exists in the image already.
For things like GPG and Dropbox we don't have any native capabilities and unless you want to build custom images that you added more packages to (do-able but probably more work than you're looking for as we build everything from source) the main escape route will be using Docker (installed as a Kodi add-on) to run a container that provides whatever binary that you're missing. You get bonus credit for authoring your own container that adds all the missing stuff in one container to avoid running loads of containers (overhead you don't need, and the one thing that's likely to result in high temps etc.).
NB: While I understand that some users like to monitor everything, the controlled and appliance-like nature of the distro also largely eliminates the scenarios where general purpose distros drift into bad shape over time requiring monitoring. LE is super lightweight and highly optimised for Pi hardware and with normal movie watching duties the only thing that's needed for avoiding high temp and under-volt scenarios is a half-decent passive or fan-cooled case and the official PSU. I've managed enough infrastructure over time myself to understand the inner need to monitor, but watching movies is more fun 
ISTR it's not functional unless "sync playback to display" is enabled .. and for general best results with Kodi on a normal TV you want to leave that setting disabled.
That patch is included in the newer kernels used in LE12 nightlies, so updating will make the harmless but user confusing message go away..
I'd update to current nightly images (LE11 or L12) as there are some improvements that might be relevant.
I use the update option in the settings for Libreelec so i think it will choose the right one.
Nope. It will only see that you're using the Generic image and give you the default image which is non-Legacy. You'll need to do a manual update via SSH.
ilmich have a chat with Da Xue in Slack. If there's a way to do this he'll be interested to help.
HDMI CEC control is almost universally supported on ARM SoC hardware devices like Raspberry Pi boards (hence lots of references to it in our forums) but very rarely supported on x86_64 hardware. So are you 100% sure the GPU supports CEC?
An issue I see with LE12: If I scroll in a stream (e.g. ARD Mediathek), the player freezes immediately and sound stops somewhat later. But maybe that is also a settings issue, I just used the default config, I just configured wifi.
I'd guess this is an HEVC stream because seeking in H264 generally works well and HEVC is mostly play/stop/no-seek .. depending on the underlying media stream (some stuff I have seeks fine, most isn't so good though) as the HEVC decoder needs work.
Overclocking instructions for RPi3 are generally applicable for CM3 too. I used to run some moderate OC with my Slice box, though that's so long ago now that I can't recall the actual details of the options used.
Start by telling us what binaries or data you need and we can give some specific advice on how to get them. There is deliberately no way to install deb/rpm packages in the OS but that's not necessarily the end of the story.
LE deliberately blocks web browsing and browser download from the add-on repo because there's an ecosystem of downstream or parallel codebase forks out there and we need to avoid the support activity that comes from users trying to run our binary add-ons on something not designed to run them. The best and largely only way to browse the repo is .. from the Kodi GUI.
The next planned update will be K21 beta 2, which I guess will be soon-ish.
You'll need the Generic Legacy image for nVidia GPU support. It should work, but the only proof is trying..
Are you using adjust-refresh and whitelisted modes to play media at native resolution/refresh or forcing everything to 60Hz? I'm not seeing any issues from a current TVH setup and my server is 6,000Km away down a WireGuard tunnel (this generally encourages any latent issues to show up).
I'd recommend whitelisting the 3840x2160 modes as it's a more accurate match for broadcast media. The 4096x2160 modes can result in vertical black bars being shown.
WARNING Incorrect checksum calculated on downloaded file: got e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 wanted e13f6f118cfbbdc0b6e0edd5e3504abd96a8d0e33dc67cba31c6942c449f77a
^ The SHA256 checksum for the package has changed on the server end (it happens sometimes) so you need to edit the package.mk file and either correct the PKG_SHA256 value or null it by setting PKG_SHA256="" and then validation will be skipped.
Add-ons > Install from repository > Kodi Add-on Repository > Look and feel > Languages > Italian
No idea about the World Live TV add-on, this does not appear to be from the Kodi repo. I suggest you contact the add-on author.
