In fact, maybe your public key idea is compatible with my last point. Just come up with a url scheme that means “this feed’s primary URL is actually a public key”, and then feed authors can optionally switch to that.

@falsifian@www.falsifian.org tag:twtxt.net,2024-09-08:SHA256:23OiSfuPC4zT0lVh1Y+XKh+KjP59brhZfxFHIYZkbZs? :)