Just wanted to say that for most use cases there is a better way to do things than using port forwarding. And by that I mean by using something like Tailscale.
So, maybe before you start looking for an alternative to Mullvad have a look at the possibility of dropping port forwarding first and improving your security at the same time.
Especially when you will still be able to use RedReader for free since it has been spared, at least for the time being. So, probably only people who really like Infinity and don't want to switch to another app. Even with RedReader though you still won't have access to NSFW.