Might consider good old x509 certificates, mTLS authentication. You can query and find peers but don’t exchange any data with them unless they can present a certificate signed by whatever issuer. Agree its probably an enterprise upsell because the openssl tooling is a PITA if you’ve never done it before, but somebody pointed me to KeyStore Explorer [0] and I’m going to give that a try to be my own certificate authority.

I wish it could be a more mainstream, hobbyist auth solution tho, it’s completely free and open and self sovereign etc etc and makes strong security guarantees, just a steep learning curve to grok what’s happening. I think it would be a big achievement if somebody slapped a friendly API / wizard over configuring a CA and creating certs to install on each of your robots / IoT sensors whathaveyou. Corsha [1] is one provider in this space, and Yubico is contributing too [2], allowing you to sign cert requests with your Yubikey.

[0] https://keystore-explorer.org/features.html

[1] https://corsha.com/

[2] https://www.yubico.com/resources/glossary/what-is-certificat...