Tried following GRUB2-EFI instead of GRUB2-BLS (How to change to it? Reason: cannot see Windows), instead of installing a working GRUB of any kind it gave me a prompt for a password for an unknown partition UUID that threw an invalid password no matter the password (tried typing it both in native layout and US layout several times). Ended up chroot’ing in a rescue environment and restoring the old bootloader. Will likely move that diagnostic branch over there.