Show a pop-up message from outside OP

[Demo]

Just a short question before I start on something that's possible out-of-the-box.. is it possible to show a pop-up from, let's say, a bash or python script running on my system? If not I'll try to create a very simple plug-in which will add a REST API endpoint that will accept messages and show them as pop-up in OctoPrint.
My purpose for this would be to schedule a script that will check for system updates and show a message with the number of updates available.

[Charlie_Powell]

There's nothing like that, already available - sounds like a job for a plugin.

[Demo]

Thanks, I'll give it a go then. I don't think it should be that hard to do, but I don't want to reinvent the wheel either