What’s an example of a well made GTK or QT app in your opinion? And what would be the steel man Web app to compare that to?

Telegram Desktop (Qt)

We might contrast that with Slack, yes?

This thread comes to mind: https://www.0xsid.com/blog/wont-download-your-app With Slack that’s trivial, Telegram impossible.

Except Telegram Desktop is opensource and they also have full-functional Web version.

But tdesktop is really well-made Qt piece of software, snappy, feature-rich and multi-platform.

Interesting, at first pass I’d say the source availability has little to do with the topic at hand. But on second thought it might be rather significant. No company would finance making 2x identical cross platform apps, but if you have a pool of OS folks who are free to contribute at their leisure, the calculus changes a bit.