[Request] Acer XC-605, MS-7869 Ver. 1.0, NVMe-boot support

I would like to continue using the cute little ACER XC-605 desktop PC which currently boots from a hard disk. An SSD would have to be installed for effective use. Instead of a SATA model, I would like to use an NVMe model that I would like to connect via one of the idle PCIe slots via an adapter.

The installed mainboard is a MS-7869 Ver. 1, the current BIOS is an AMI-BIOS version P11-B4.
I’m dealing with the subject of BIOS modding for the first time and after reading what I’ve read so far, the project should be feasible with this model. Although it still has a conventional-looking BIOS without mouse operation, it apparently boots via EFI and CSM is deactivated.

Since I still feel too unsure about modding myself, could someone build me the necessary BIOS?

PS:
Does a clean install of Windows have to be carried out in any case, or would booting from the cloned image of the current installation on the hard drive also work?