FYI a lot if not all of the core docs actually have tabs on any code samples to switch between c# and gdscript so while tutorials from third parties tend to focus on one or the other, the core docs are a bit better.

I've started going through a tutorial on youtube from I think finepointCGI about a horror game in Godot, he is actually doing it twice, once with GDScript and once with c#, so if you want to see someone with some godot experience using c# give it a look.