F# is a niche language among .NET developers, because adopting it closes the doors to lots of enterprise tooling (including Visual Studio designers), that only consider VB.NET and C#
Visual Studio designers are an abomination. Once beyond anything trivial it is slow and buggy and a pain. Look at FUNC.UI https://github.com/FuncUI/Avalonia.FuncUI to see how code only UIs could look.