How exactly do you block sftp at the firewall if it uses the same port as ssh? From the firewall's perspective it is just some encrypted traffic inside ssh tunnel. I think that you might be mistaking sftp with ftps (ftp through ssl/tls tunnel), these are different protocols. I suggest you try connecting to any box you have access to using Sftp protocol and ssh credentials and see the result.
I completely forgot that sftp is on 22. Like I said, I block the port until it is properly knocked. In any case, I usually don't need the convenience of an IDE. It's much easier for me to just do everything over ssh. My IDEs (Jrtbrains, VS Code) use VIM keybindings too. And I could just as easily apt get vim on the server.
In any case, it's literally been years since I've had to.
