Well, Linux has won the cloud meaning it is and will be a primary target for .NET.

I'm not sure what vested interest MSFT had in some of the changes introduced for iOS in .NET 8, but now it can be targeted with NativeAOT too, so there is clear investment and dev effort both from community contributors and MSFT employees to support various platforms.

Somewhat arbitrary example, there is also a project to support RISC-V (https://github.com/dotnet/runtime/issues/84834).

For both reasons mentioned above, yes. Even internally, many teams in Microsoft are shipping containers on Linux for prod services.

Azure is also the big moneymaker, so these days they want all their technologies to have Linux support since that's the dominant cloud OS.