I think that it's always been possible. There just isn't a market need for it. Sidechains were BEFORE forks, for those who don't know the history.

Ordinals became possible with Segwit also. Took years for that to finally get implemented and where is it now? Seems like this garbage has turned out to not be worth anything, and I'm sure the miners all thank you fools for backing them up in the hardest part of the 4 year cycle.