@ bpg
This thread is dedicated to NVMe boot using the Clover EFI Bootloader.
There is another thread dedicated to NVMe boot using Duet-Refind here.
So you may like to ask your question in that thread.
Or, since you have legacy BIOS PCs, you may like to try Clover bootloader instead (read the tutorial at the beginning of this thread).
Altenatively, you may like to start a new topic under the ‘NVMe support for old systems’ section with your question.