Actually it's super-easy, barely an inconvenience. Dedicate a portion of your site to notifications. Allocate the URL there with a blank page that has a meta 4

Actually it's super-easy, barely an inconvenience. Dedicate a portion of your site to notifications. Allocate the URL there with a blank page that has a meta 404 tag or something. When blog post is live, replace the meta 404 with a meta redirect to the real permalink. You can do an all-manual URL shortener for QR codes the same way. That means you can also have a QR code for this kind of subscription, which is cool