So the issue (i believe) was I had left CSM/Legacy BIOS enabled without realising it and bazzite installed non-efi. Because windows was EFI it was not visible in the non-efi grub menu.
Updating the BIOS so that i could disable CSM/Legacy BIOS (and Secure Boot which was also not present in my earlier bios version) meant i could reinstall bazzite using grub-efi.