I'll be collecting here info about abilities and restrictions of various devices (decoding only!).

• Intel Gemini Lake - Two HDMI 2.0a ports, MPEG-2 1080p(up to High), 10bit HEVC up to 4K60fps(Main 5.1), 8bit H.264 up to 4K30fps (up to 5.1), VC-1 4K (Advanced/High), VP9 Profile2 4K 10-bit, no HDR support at all for now
• AmLogic 905X - One HDMI 2.0b port, 10bit HEVC up to 4K60fps, 8bit H.264 up to 4K30fps, VP9 Profile2 4K 10-bit, HDR10, HLG support, depend of implementation
• AmLogic 912 - One HDMI 2.0b port, 10bit HEVC up to 4K60fps, 8bit H.264 up to 4K30fps, VP9 Profile2 4K 10-bit, HDR10, HLG, Dolby Vision support, depend of implementation
• AmLogic 905X2 - One HDMI 2.0b/2.1 port,10bit HEVC up to 4K75fps, 8bit H.264 up to 4K30fps, VP9 Profile2 4K 10-bit, AVS2 up to 4K30fps, HDR10, HLG, HDR10+, Dolby Vision support, depend of implementation
• Allwinner H6 - One HDMI 2.0b,10bit HEVC up to 4K60fps, 8bit H.264 up to 4K30fps, VP9 Profile2 4K 10-bit, HDR10 and HLG support, depend of implementation
• Rockchip RK3328 - One HDMI 2.0b port,10bit HEVC up to 4K60fps, 8bit/10bit H.264 up to 4K30fps, VP9 Profile2 4K 10-bit, HDR10 and HLG support, depend of implementation
• AMD 2200-2400G - DP/HDMI 2.0b ports, 10bit HEVC up to 4K60fps, 8bit H.264 up to 4K30fps, VP9 Profile2 4K 10-bit, HDR support even on old motherboards
• Nvidia GPUs 10xx - HDMI 2.0b ports, 12bit HEVC 420 up to 8K, 8bit H.264 up to 4K and lot of fps, VP9 Profile2 4K 12-bit, HDR support
• Nvidia GPUs 20xx - HDMI 2.0b ports, 12bit HEVC 444 up to 8K, 8bit H.264 up to 4K and lot of fps, VP9 Profile2 4K 12-bit, HDR support