The situation is not what they are trying to imagine. Several independent projects are working on HW. Not everything is working and the process is not fast, but there are already the first results. By the way, these works are carried out including the use of equipment Khadas VIM\VIM2. If you need a working solution for full-screen video playback right now, there are working HW variants with kernel 3.14\4.9. There are mostly dissatisfied with those who want to get everything quickly and for free.
p.s.
I recommend to try the latest image of Armbian 5.64. Video playback is not ideal, but is acceptable for “home” use in mini PC mode. And for high-quality full-screen video 1080p and 4K you need to use specialized images LE (in which there is HW and everything is optimized for video).