My bad here, I didn’t mean AAC, but ALAC (lossless) and other Apple’s own mp4 variants. Indeed not sure how’s the support in core Android, although I’d guess ALAC should be since it’s part of mp4 specification.

I haven’t goofed around with it in a while, but some ~10 years ago when I was doing tech reviews I was looking into ALAC quite a bit and was surprised how nice it is, and apparently easy enough to implement that even lots of hardware devices supported it without even advertising it. Also 3rd party audiobook players can often deal with Apple’s audiobook DRM.

Basically, Apple did surprisingly well with audio formats while also supporting some open formats (at least in hardware), so maybe that’s also a reason why I’m not so adamant about formats being 100% free from the start, as long as they get the codec ball rolling.

But again it’s been 10 years since I was looking into this closely so I’m very fuzzy on the details.