IMO in a raid config, used drives are fine, especially if you have backups.
I bought a few before the prices were crazy and they havnt been on for a while but never had issues with them. Funny enough, I had more issues with the used motherboard than I did with those drives lol.
I tried umbrel a while back and it was alright. Some stuff just didn’t work for me all together but it was quite a few years ago that I tried it.