I need a very simple method for non-advanced users to share each other's screen explicitly when they need help. They're running XFCE on Manjaro and the machines involved are using Tailscale. Edit: SSH access is also available, with key authentication.

I need something super simple because they are remote from me and from each other and any graphical setup will have to be assisted sight-unseen over phone. So ideally just (1) install something (which I can do for them over SSH), (2) pick something from the Applications menu and maybe (3) press a big "START" button.

It's also ok-ish if the remote capability is present all the time and I can connect without their explicit permission, but you can see why it would be best if they did something to enable it...

I've been looking for a solution but all I find is stuff that's way too complicated OR starts a new desktop session instead of showing the current one.

Edited: to clarify I'm not the one who will be remoting-in and to mention SSH is available.

TIA