I purchased a “Raspberry Pi M.2 HAT+” to install M.2 drive on my Pi 5. There are two problems with it! First, if you have a touch screen mounted to the Raspberry Pi, the supplied M.2 hat mounting hardware doesn’t work. The standoffs are double female threads – you have to cut the heads off screws and use the threaded portions as studs through the Pi board to the standoffs from the touch screen. I had some spare 2mm (?) screws that I cut down and used. (I’m used to DIY, but this is asking a bit much.)
A much more serious problem is that the pins on the GPIO header supplied are about 6 mm too short! (The supplied head has 10 mm long pins, they need to be 16 mm or longer.) They do not extend past the M.2 hat so you no longer have any access to the GPIO header!
If the M.2 hat was intended as a single layer hat, it should be advertised as such. But then it eliminates much of the functionality of the Raspberry Pi!