Hi,
currently I'm booting from mirrored SATA devices, but I also want to setup a TX1320 to boot from mirrored NVMe. I assume you want to use some software RAID for this.
First: the bootloader/kernel is always read
from one device only. After loading the operating system kernel, it can access the mirrored boot devices as intended. But if things are set up correctly, the second boot device will be used to load bootloader/kernel, if the first device fails.
You can use
two M.2->PCIe adapters and put each in it's own slot, e.g.
GLOTRENDS PA12 (note: these also have an additional slot for a SATA SSD). As I did not notice anything about PCIe bifurcation in the BIOS, you can not use cheap adapters for two M.2. Instead, if you want to use a single PCIe slot only, you have to buy something with PCIe switch chip (e.g. ASM2812 chip). An example for these type of adapter is
GLOTRENDS PA20. These are more expensive an also draw more power (IIRC my measurement was ~7 W for the adapter only).