unix – MacBook Air M1 dual boot from external SSD

I have a MacBook Air M1 512 Gb and I want to be able to use Linux (Asahi), since it’s necessary for my university.

However, I don’t want to use internal space and I thought that I could maybe use an external SSD dedicated to just Asahi. So when the SSD is plugged in, I get the option to select which OS to use and when it’s unplugged it automatically boots into macOS.