Just a quick thought. These days you can create a special partition in the first part of your drive and just boot from it. No grub, no config really.
You might want to take a look at EFI and an EFI system partition perhaps?
I am considering a Fairphone 4 (or seeing the recent news, maybe 5?) for Lineage. Anyone using this combination already, quirks to be aware of, battery life, camera quality, etc?
Signal