Hi
In Germany best is here:
https://www.nrg-systems.de/index.html
This is the detail page, the modell is a APU.4D4 (Quad Core CPU, 4 GB RAM, 4 Intel NICs)
https://www.apu-board.de/
Get a 120 GB SSD, and you also get a top Proxy!
Here you also support the Project:
https://www.applianceshop.eu/security-appliances/security-appliances-desktop-and-wallmountable/opnsense-based-desktop-12.html
Nice hardware, pre assembled… The one with two OPNsenses in one box, along with two PSU (Power Supplies) is nice for a space restrained Rack, with a High Availability 1HE Dual Firewall. Both OPNsenses are really completly separate…
My 2 cents
Andy