I'd argue JXL is fairly used, least in the photography circles I involve myself in. DNG 1.7 added JXL compression and at least for sharing raws around on the web it's been a boon.
Lightroom will output 16 bit ones but you can go up to 32 bit far as I'm aware.
Of course normal JXL files support similar as well, with meaningful progressive decoding at better ratios.
If you’re talking about embedded inside DNG, then you’re talking roughly a maximum of 14 bits. There’s not really much capture beyond that , whereas this + the other formats I listed provide 16 bits. That’s quite a significant jump
Of course normal JXL files support similar as well, with meaningful progressive decoding at better ratios.