I’m a little confused about what I’m meant to be doing in this part
You’ll need to find the partition number and the reference to the disk in /dev for your boot partition /dev/disk/by-partuuid/172a0183-3a89-4b78-b1b3-d016ca6675f7. You can try using ls -l /dev/disk/by-partuuid/172a0183-3a89-4b78-b1b3-d016ca6675f7 to see where it points (i.e. for /dev/sdb2 you would use --disk /dev/sdb --part 2).
I also, get this error “invalid numeric value Y” when trying to manually register systemd-boot