It’s huge in the game dev world, with Unity and Godot. .net also had a reasonable community on mobile for a while thanks to Xamarin, but I cannot imagine that many people using it for new mobile projects in 2026 (outside of game dev I mean).
It’s a very decent language (I mean C#) and runtime, I wish it had more market share in the startup world.
Unity is still using Mono these days which is missing basically all of the C# and .NET improvements from the past... 10 years now?
Godot was using Mono too but has since switched to .NET in version 4.
Still a great language and I hope Unity can hit their target to switch to .NET soon!
An enterprise shop I co-op'd at was porting one of their apps from Xamarin to MAUI when I worked there, but certainly it doesn't have much mindshare (if any) amongst SE undergrads at my university.