The latest .NET version is fully cross platform.
They only go far enough to bait and switch you and then after they get you they cut funding for maintenance and the cross platform bits rot away.
.NET Microframework makes it runnable on IoT.
I'm also pretty sure that embedded Java is widely deployed in IoT applications.
PS4 (MonoGame/Mono) XBox One (.NET Core on the future and MonoGame/Mono)
At least you can run c# code on those platforms. Java though is unlikely to ever happen.