So I unplugged my windows drive so that it wouldn’t be viewable when I reinstalled and Manjaro booted from EFI successfully.
I think this was a problem with my specific motherboard BIOS since it didn’t even show it as a bootable drive beforehand.
Only installing a single drive at a time and they both boot fine individually.
When they’re both installed, the one most recently unplugged doesn’t show on the boot menu.
Thank you all for your help.
I wouldn’t recommend MSI B550 Mortar Wifi