Magisk is a way to root your phone, you need (at least temporary) root privileges to switch that switch back to ON. I wrote a short tutorial in the past (which might be slightly outdated, don’t use that boot.img), but there is still a risk involved when locking the bootloader, so I wouldn’t recommend it if you depend on your FP for anything essential. Worst case scenario you’ll have to get if fixed by support for up to 30 euro.
get_unlock_ability tells you the state of that OEM unlocking switch you had to toggle before unlocking the bootloader. Doesn’t matter much if you don’t intend to relock your bootloader, but if you do and something goes wrong, that variable being 0 means you wouldn’t be able to unlock it again to fix it → 
But before any of this becomes relevant, you’ll need a working Calyx installation first 