Yeah there’s a bunch of them out there. I’ve had one running for a while now. Don’t have the specific model but it’s something like this: a.co/d/2v5M3U3
This is what I do though technically it’s a container on Proxmox. Otherwise I’d recommend one of the LibreComputer boards. The Le Potato one is solid and cheap though also over kill for just a PiHole.
A “free” option if you have some PC hardware lying around is to run OPNsense/pfSense instead of buying a dedicated box. I say “free” since it will use more power and require more time to configure and manage.
Alternnatively, I ran one of TP-Links AX consumer router/AP combos for several years and it was solid. Even had an OpenVPN server built in. I can look up the exact model if you’re interested.