Apple ain’t going to enable features they don’t support on safari.
That's why there are regular "Webkit features in Safari X": that something is added to webkit does not guarantee it'll land in Safari, ever.
Hell, it took 18 months and 2 iOS/macOS releases for the AVIF support to go from landing in Webkit to landing in Safari. And that was something Apple wanted.
Neither was webm support, but that didn't stop them from taking several years to implement it (and even then it was half-finished). Apple clearly wants to play the superiority game with their own codecs. They have zero incentive to support any codecs they didn't build, and have been known to abandon standards that they help develop.
Nothing is technically impossible for Apple, but codec support is stuck between an ideological/financial rock and a hard place.
And on the other end you have Google who threatens others if they don't bend over and implement Google's codecs in hardware [1]. The codecs space is, and has always been, a game of shitty players.
[1] e.g. https://www.protocol.com/bulletins/av1-android-14-requiremen... and https://www.protocol.com/youtube-tv-roku-issues
To be clear I didn’t say I’m holding my breath. Just that it’s not “obviously” impossible.