These use the A series chip, and even supporting new M chip revisions has been enough of an undertaking that I wouldn't really expect this to get Asahi linux anytime soon....
And apple can lock down the bootloader to be closer to the iPad/iPhone at any time with no notice, and based on their past actions, it would be quite in-line with their character to do so.
The terminal app is not iterm. But Apple's own Terminal.app
And no there's no package manager but there's brew and macports.
But we know there’s lots of other models that they’re already working on. We don’t know how similar or different it is from an OS perspective.
Reverse engineering needs a lot of time and hard work, which may not be worthwhile.
Sometimes someone does this work, and everyone may benefit from it, but you should never count on this happening, unless you do the work yourself.