Despite some recent issues I've had with the telegram client on a certain rolling release distro, it is still by far the gold standard of cross platform native apps in my mind.

IIRC its all/mostly CPP. Runs natively, can handle all sorts of weird desktop configs easily. Its just very snappy and a pleasure to use even on fairly low-end systems. I've installed it on a 32-bit laptop from 2004 and it was very usable.

People make some statements about it being Russian owned, and at the end of the day I don't talk about anything important on there, if a Russian team wants to make a world-class cross platform native chat app that I can direct friends/family to and know they won't have any issue getting started, I'm happy to support it.

I hate the web-appification of every desktop app with a burning passion.