You can already do this with VNC or Xpra (the latter is a screen/tmux for graphical applications).

For a remote Linux system you can also do a lot over plain SSH as well.

It's open-source, so just build it yourself with the tiny change. Something this trivial could be done with a 30 second prompt at this point, so there's not even an excuse of "too much effort."

I will note that the XKCD password scheme being proposed there is, in fact, completely insecure. A single modern consumer GPU can crack "four random English words" in a day. You can argue that it's the user's choice to be allowed to use insecure passwords, but arguing that that scheme is actually secure is just wrong.