In a signature context, you probably want someone else to know that "you" signed it (I can think of other cases, but that's the usual one). The way to do that requires them to know that the key which signed the data belongs to you. My only point is that this is actually the hard part, which any "replacement" crypto system needs to solve for, and that solving that is hard (none of the methods are particularly good).

> The way to do that requires them to know that the key which signed the data belongs to you.

This is something S/MIME does and I wouldn't say it doesn't do so well. You can start from mailbox validation and that already beats everything PGP has to offer in terms of ownership validation. If you do identity validation or it's a national PKI issuing the certificate (like in some countries) it's a very strong guarantee of ownership. Coughing baby (PGP) vs hydrogen bomb level of difference.

It much more sounds to me like an excuse to use PGP when it doesn't even remotely offer what you want from a replacement.

I think it should be mostly ad-hoc methods:

if you have a website put your keys in a dedicated page and direct people there

If you are in an org there can be whatever kind of centralised repo

Add the hashes to your email signature and/or profile bios

There might be a nice uniform solution using DNS and derived keys like certificate chains? I am not sure but I think it might not be necessary