I'm in a similar boat with storage stress, I have a mini Dell Optiplex with a single nvme and 2.5in drive available.
I have bought a small m.2 to 2 x SATA card, but I really need a nice housing + power for internal 3.5in drives to make it useful.
Anyone have experience with this? All I see online are USB drive caddies, I'd really love it to be SATA.
Oh what I'd give to have the space and cheap enough power for a full rack setup.