So far I found that there is an option to boot into EDL 9008 mode:
https://blog.tho.ms/hacks/2021/03/27...-note-air.html
It works only if I can reach adb.
I found instructions on how to enable adb from recovery:
https://gist.github.com/varhub/7b955...fde2300fcfd0bd
However, if I understood correctly, Magisk replaces the recovery. So it turns out I cannot enter recovery with rooted boot.img? Or am I missing something?