Welcome to the forum.
I have to pay attention when looking at mini pc’s. Yeah, M.2 2242 doesn’t tell the whole story since M.2 is the plug and 2242 just tells you the physical size of the drive. Then they try to confuse you with the B key and M key.
NVMe is high speed, PCI express interface and a lot faster, like 10 times faster usually. SATA is slow, stuck at 500 MB/sec, which is the one we have. SATA is a lot less common, too.
So, I need a M.2 hard drive. What length can the drive be? 42mm or 80mm or something else? What format can the drive be? NVMe or SATA? NVMe can be much faster. Some devices have two M.2 slots with one of each.
So, if you’re looking at buying a device with a M.2 slot, my preference is to get one with NVMe compatibility.