NVMe drives are M.2, they don't look like it - they are.
Anyway, your best bet is the internal adapter. It's not that tedious, seriously, it takes about two minutes..
NVME is not M.2
And M.2 is SATA based, while NVME is PCI-e. Most enclosures especially state that it is not compatible with NVME, while the others just have an outdated description.
Consumer NVMe SSDs use the M.2 form factor.
M.2 carries: SATA, PCIe, USB2, USB3, SMBus, SDIO, UART, .....
M.2 SSDs come in SATA, PCIe AHCI, and PCIe NVMe. Any of which will work in either slot on the board in this machine. Wifi cards are M.2 now, too.