So you're working remotely and a colleague asks a question...

You spend five minutes telling him click on the Foo button, no not the BAH, the one above it, no the one below that one, ......

And the you enter this command on the command line...

What is your favoured linuxy opensource tools for this sort of collaboration?

Do you mean face-to-face real-time collaboration?

You might want to take a look at jitsi. My LUG has been using it for meetings in these viral times and it works quite nicely.

As far as I can see it's a drop in opensource replacement for Zoom, and hence will have the same problem... I can see the other guys screen if he shares it... but I can't type on his command line or click his buttons.

It sounds like what you are looking for is some sort of VNC connection which will give you direct access to someone else's machine.

A web search for "remote computer vnc" will turn up a number of articles that might help.

Unfortunately, I don't have any personal experience with this, at least not for many years. Back in my Windows days, when I was wearing a headset, I was allowed access to a remote computer by a client's IT department, but I didn't set it up, they did.

Now that you've provided more information about what you are looking for, perhaps someone with more first-hand experience than I will join this thread.

Used to be called "Remote desktop".