Just pick up the nanopi r4s or r6s. Fairly small, but with nice specs and support in openwrt. The r6s isn't supported by openwrt 23.05 but you can get the friendly elec fork or get a community rebuild of openwrt with a later kernel that supports it. You'll get a router that can work at line speed (1Gb or 2.5Gb) even if you use features like SQM or wireguard.