So I have TrueNAS Scale in use, and it works wonderfully. But now I've switched to a Node304 building, there's no more room for it.

First of all: I have no experience in this regard. Basically, the question is whether the PCIe lanes can be split on the Dell server (BIOS setting). I had already used the card on a mainboard where I could only split by 2 and could therefore only use 2 NVMe drives.