Implement a cryptographic web of trust system on top of Lemmy. People meet to exchange keys and sign them on Lemmy’s system. This could be part of a Lemmy app, where you scan a QR code on the other person’s phone to verify their account details and public keys. Web of trust systems have historically been cumbersome for most users. With the right UI, it doesn’t have to be.
Have some kind of incentive to get verified on the web of trust system. Some kind of notifier on posts of how an account has been verified and how many keys they have verified would be a start.
Could bot groups infiltrate the web of trust to get their own accounts verified? Yes, but they can also be easily cut off when discovered.