> And is Postgresql a 2nd-class citizen?
No, it is not.

Microsoft maintains the Npgsql project[0] and I say that it is a very capable, feature rich adapter.

I have not used C# with SQL Server in almost a decade.

[0] https://www.npgsql.org/

Also the recentish addition of multiple line string literals makes dealing with Postgres's case sensitivity a lot easier to manage.