I created a branch in my repo with all the newest stuff from Bootlin and Allwinner LE branch. When it will be usable, it will be merged in LibreELEC/Allwinner repo. You can find it here: GitHub - jernejsk/LibreELEC.tv at aw_hw_dec
It has some additional VPU driver fixes from me which I already reported to Bootlin.
HW acceleration kind of works. MPEG2 should work in general, but please note that there is a bug in FFmpeg VAAPI handling code. As long as you have properly formed MPEG2 files, you should be fine. If not, you might receive green screen. Note that exactly same bug is visible on PC with same video, FFmpeg and Intel VAAPI, so it's not Bootlin driver fault. H264 is work in progress and most of the time, there are visual artifacts and sometimes video won't even start. Those issues are all known, so no need to report anything yet.
So for now, this is not yet usable for daily use. Once driver becomes more stable, I'll provide community build for wider testing.
BTW, if someone wants additional H3 devices to be included, just make a PR against Allwinner branch with necessary. No need for constant manual patching.