If the source is available, how much work is there to add ARM support, other than compile it for ARM? Some package managers compile from source at install time anyway. I'm sure there are various "I-think-you'll-find-it's-a-bit-more-complicated-than-that"s. I'm interested to learn what they are.

It depends heavily on the project. Maybe it's using a bespoke/old build system that doesn't support targeting arm, obviously any uses of assembly need translation, bugs/compilation issues regarding signed-ness of char in C/C++, or page size. Those are at least all the issues I've encountered.

When Itanium was new, HP contracted with Progeny Linux to help them port Linux software. Despite the fact that Alpha had paved the way for 64-bit support it was a long effort.

It practically makes them much better, no magic required.

https://wiki.debian.org/Arm64Port

> 98% of Debian is currently built [for arm64]

For most applications ARM support should just be a recompile.

ARM has been a mainstream target for Linux years before Asahi linux. See Raspberry Pi for example.

I tried to use RaspberryPi last year. Quite a few apps weren't available for it because there are no ARM versions.

Can't remember which (calibre was one of them, maybe?), but it was enough for me to reconsider using it

IIRC Calibre supports ARM architecture since 6.0 release, which was July 2022

It was probably not available at the time I needed it :)