Supermicro servers offer compatibility lists for these NVME products such as this:
www.supermicro.com
Servers offer hot swappable trays which don't work quite well. DM if you want to hear my experiences.
It is simply easier to work with a U.2 in the drive bay than to pop open the chassis and add the gum stick. Note for the U.2 drive you will have to check the server and mobo spec and purchase the appropriate cable to hook up the mobo to the backplane into which the trays plug into.