4:2:0 chroma subsampling might be useful for compatibility. So, sticking with 4:4:4 might or might not be ideal. There are codecs such as H.264, where using 4:4:4 substantially reduces compatibility. Though, there are others like JPEG where it seems fine. Perhaps there are AV1 hardware decoders that only support the AV1 main profile? For the web, there is the HTML picture element where an avif image can be automatically selected by supported browsers and images of other codecs can be used as fallbacks, but maybe it would display wrong and not fall back if avif is supported but 4:4:4 isn't?