A refurbished thin client from eBay. Or a refubed sff/usff.
They are pretty much the same price these days, and come with a case/PSU.
If you don’t need the GPIO and special connectors that a raspberry pi has, sff/usff is going to be cheaper, has upgradeable ram&sata and some have pcie3.0 slot.
Running pihole (let’s be honest, a huge reason people buy a pi)? Get a usff/sff, slap an SSD (probably the cost of a raspberry pi case/PSU/SD-card) in there and an intel i340-t4 4port NIC (this is extra. Can just use the onboard NIC), and install proxmox. Then run pihole in a VM. And now you have spare capacity to run a whole bunch of other fun things, with the safety net of snapshots and backups so if you mess up a config you can just roll another VM.
That’s about 4x the price for pihole. Pihole runsnon a zero 2w with headroom to spare. So it’s 16€+SD card+power supply you got lying around. What you described is a pretty convoluted setup for that. I had pihole+ Octoprint running on a 2W before. Worked flawlessly in my setup.
