I don't think this would be practical for a static site. You still need to maintain a list of followers of your account somewhere and that needs to be dynamic i

I don't think this would be practical for a static site. You still need to maintain a list of followers of your account somewhere and that needs to be dynamic if you want it to work the way people expect it to where they follow you from other instances. Assuming you kept the @ list of accounts through some other means, if you had your webfinger setup with your public key, you could after creating new content to push up sign the publish events and push them to those followers. I don't know of anyone doing this though.