I currently do something similar.

My router is a 16GB n150 mini PC with dual NICs. The actual router OS is within openwrt VM managed by Incus (VM/Container hypervisor) that has both NICs passed through.

One of the NICs is connected to another OpenWrt wifi access point, and the other is connected to the ISP modem.

The n150 also has a wifi card that I setup as an additional AP I can connect to if something goes wrong with the virtualization setup.

Been running this for at least 6 months and has been working pretty well.