Ok, so i've made a bootloader in assembly but I think its very hard to write the operating system (the kernel) in assembly so I wonder if it is possible to write it in C#?
The question is: Can you write a C# console application and convert it to .bin or some other format which you can rawwrite to a floppy and then load it from the bootloader?

Thanks in advance

Normally you cannot.
C# is not compiled to native assembly by the compiler but to IL (Intermediate Language) This IL is translated by a JIT(Just In Time) compiler in instructions a computer can understand. I think this scheme was first implemented by Java. It makes your code as portable as possible. But as you see it has some drawbacks, use C or C++ for what you are trying to do. Succes!