I've got one running in an Argon case with an M.2 expansion base. That's the first one I got and it's running home assistant and the omada controller.

The rest is racked in this awesome rack thingy and I believe the SSDs is connected using these (regular 2.5" SSDs). However, it was a while since I got mine and I'm not sure they're reliable anymore. There's usually good info on the Pi forums, I don't have time to look at the moment but might have a browse later as I think I've only got 1 or 2 left in the spare drawer.