I had a setup similar to this for a year or two that ended with an hdd destroying itself one night. Probably because of the drive and not the usb enclosure I was using. Until then it worked fine, it’s definitely a viable route.

If you can swing a desktop pc case it’ll probably end up easier and cheaper and have some headroom for upgrades, that’s the route I went down after trying an escalating series of mini-pcs and running into their limits one too many times.