I'm currently running Syncthing, Forgejo, Pihole, Grafana, a DB, Jellyfin, etc... on a M910 with an i5 (6th or 7th Gen) without problems.
These are great and the M920q is also nice.
At 100 to 160 used these are a steal, just test the disks before you commit to long term projects with them (some have a fair bit of wear). Its newer cousins quickly climb in price to the $300+ range (still refurb/used)
The bleeding edge of this form factor is the Minisforum MS-01. At almost 500 bucks for the no ram/storage part it's a big performance jump for a large price jump. This isnt a terrible deal if you need dual SFP+ ports (and you might) and a free PCIE slot but it is a large price jump.
I’m pissed at Lenovo for making the perfect machine for a home server, and then cheaping out by not adding the $0.50 M.2 connector on the back of the board. 2xM.2 + 1xSATA requires upgrading to “Tall” Intel NUCs if you want 3 discs.
Something with 8th gen i5 can be had for about 100-150 USD from ebay, and that's more than powerful enough for nearly all self-hosting needs. Supports 32-64gb of RAM and two SSD.