Even with AOT compilation, as someone who loves C# and also does embedded development in C I would personally say a garbage collected language like C# has no place there.
not everything running on a 20-mips 32-bit microcontroller with 2 kibibytes of sram needs to be hard real time and failure-free, and of course the esp32 has hundreds of kibibytes
and, correct me if i'm wrong here, but doesn't c# allow you to statically allocate structs just as much as c does? i'd think you'd be able to avoid garbage collection about as much as you want, but i've never written much beyond 'hello, world' in c#
c# has the concept of value types (which structs are), which are stack allocated. Generics have seen more and more instance of getting a Value type like Value Task for stack allocated async objects. But if you add a class as a member of the struct that is going straight to the heap with all the GC stuff that entails
what about global or static variables of value types? i mean in theory you could stack-allocate whatever you want in your main() method and pass pointers to everything, but that sounds unusably clumsy. but with global variables and/or class variables there would be no problem except for things that inherently require heap allocation by the nature of the problem
Static fields may be placed on Frozen Object Heap. The values of static readonly fields may not exist at all if the ILC's static constructor interpreter can pre-initialize it at compile-time and bake the value into binary or codegen. Tiered Compilation does a similar optimization but for all cases. This is with JIT though which is not usable in such environment.
Otherwise, statics are placed in a static values array "rooted" by a respective assembly. I believe each value will be contained by a respective box if it's not an object. This will be usually located in Gen2 GC heap. My memory is a bit hazy on this specific part.
There is no concept of globals in .NET the way you describe it - you simply access static properties and fields.
In practice, you will not be running .NET on microcontrollers with existing mainline runtime flavours - very different tradeoffs, much like no-std in Rust. As mentioned, there is NanoFramework. Another one is Meadow: https://www.wildernesslabs.co which my friend is using for an automated lab for his PhD thesis.
Last mention goes to https://github.com/bflattened/bflat which supports a few interesting targets like UEFI. From the same author there's an example of completely runtime-less C# as well: https://github.com/MichalStrehovsky/zerosharp. It remains a usable language because C# has a large subset of C and features for manual memory management so writing code that completely bypasses allocations is very doable, unlike with other GC-based alternatives.
there are ways (byref I think?) to pass references to stack variables around. And Statics depends. Static const even with stuff like strings would just compile directly into the binary, regular static still has to end up on the Heap.
