OpenWRT

The OpenWRT pacakge is not built /or maintained by ZeroTier Inc, but some of us use it on our routers.

https://github.com/mwarning/zerotier-openwrt/

See the their wiki for instructions for routing between your ZeroTier network and physical LAN via OpenWRT

https://github.com/mwarning/zerotier-openwrt/wiki

OPNsense

Also not a package built or maintained by ZeroTier.

https://docs.opnsense.org/manual/how-tos/zerotier.html