I just found out about Turris Omnia. Its not open source but its modular like a PC. But its a router. I know it does not make sense so please take a look yourself

https://www.turris.cz/en/overview/

They also launched an indiegogo campaign last year that you can check out here

https://www.indiegogo.com/projects/turris-mox-modular-open-s...