So what you are looking to do is:

Text:

Signature:


BUT not tell people what address it's signed with.

So, until there is a NEED to prove you wrote something there is no way to know if it's valid or not.

So in theory 10 years from now I could prove that on 4-Feb-2024 because of the above text and signature I controlled the address bc1qugdlj4sghspzyx5w74xm77mn67auyzc2y6huls

I cannot see another need other than that.

-Dave