i recommend a second hand business-class workstation. micro chassis would be ideal for smallest footprint.

if youre in the states, i have a few small form factors listed on https://pleb.parts/

im open to shipping without a hard drive (e.g. bring your own) or with an ssd. ping me with any needs and/or questions. happy to assist.

also recommend picking a small battery backup unit. an apc 425va is a good fit. power protection is important!