You (knowingly?) picked the one counter example, lol. Web of trust is the one application of PGP/GPG for which there isn’t a product ready replacement tool to point towards. GPG is built around web of trust, but this is generally believed to have been a very, very bad idea and the source of innumerable security problems for nearly every application that has tried to make use of it. The GPG replacements I would point to are purpose-built for specific domains and eschew web of trust:

https://soatok.blog/2024/11/15/what-to-use-instead-of-pgp/

That said, you might find what you are looking for in the Rebooting Web of Trust project, and the various decentralized identity (DID) implementations that have come out of it:

https://www.weboftrust.info/

Keybase or any of the tools inspired by keybase (foks.pub etc)