I would assume that once you have fully functional support for entire historical SoCs, the effort stops being "get most things working on most chips" and starts becoming "adapt already-working things to the newest chips". Yes, it's been years, but there's still so much hardware that Asahi doesn't have good support for yet, and that's dividing the efforts to support the newest chips. I'm sure that once all the existing chips are well-supported, new chips will be fairly quick to bring up.

I've daily driven Linux for years, even on laptops. Yet they're always plugged in because I've yet to see Linux out perform battery life of native OS's. Well, except for very niche and pared down Linux's.

Rather it seems that as time goes on Linux just outgrows old devices entirely, again excluding very niche distros. Not that it makes them increasingly efficient.

Have you seen Linux getting more efficient over time? What's your use case?