pfsense (https://github.com/rapi3/pfsense-is-closed-source)

Oracle gives free VPS, permanently free. Have a backup of these VPSes though, Oracle sometimes (haven’t experienced it myself, but some people here did) kills these VPSes.

No need to expose to the Internet. You can e.g. expose them to Home-Assistant/openHAB only, or VPN to your LAN then connect to them.

PfSense can do that