You don’t need something huge. Remove the DVD drive and the old mechanical drive from a USFF machine, stick a pair of 4TB drives in it, and put a basic debian image on it. Configure SMB with a shared folder or two, and voila: you now have a comfortable NAS for maybe £20 plus drives. Add in a sata pcie card if you can find a decent low-profile one, and that’s an extra four or even six drives. It won’t give you the cream of top performance, but it will be perfectly serviceable for a homelab.
I habitually use a clean install whenever I move OS - so much so that I’ve been buying new storage drives for the sake thereof. I actually have one ready to go for Trixie, once I finish a current project.