Is it practical to use hardware video decoders to decode the image formats derived from video formats, like AVIF/AV1 and HEIC/H264? If so that could be a compelling reason to prefer them over a format like JPEG XL which has to be decoded in software on all of today's hardware. Everything has H264 decode and AV1 decode is steadily becoming a standard feature as well.
No browser bothers with hardware decode of WebP or AVIF even if it is available. It is not worth the trouble for still images. Software decode is fast enough, and can have advantages over hw decode, such as streaming/progressive decoding. So this is not really a big issue.
No, not really - mostly because setup time and concurrent decode limitations of HW decoders across platforms tend so undermine any performance or battery gains from that approach. As far as I know, not even mobile platforms bother with it with native decoders for any format.
