Setting up an OpenBSD router is almost trivial - it's all there in the base system. dhcpd, unbound, net.inet.ip.forwarding=1 and a forwarding rule in pf.conf and you're good to go. Then the tinkering starts, of course (even wireguard's available in base). Do run a few benchmarks - my APU2 can't really live up to gbit IP throughput (iperf3 speeds were about 500 Mbps, no performance tuning ). Luckily the veb(4) software switching does reach 1 Gbps locally and my uplink is only 100/100.

Would recommend it, very nice to work with.