Is AOT compiling your binaries [1] an option for you? The starting size of AOT compiled C# can beat Go in size [2] and from there it really depends on what you do and how you do it. Some simple ASP.NET server with https and routing can comfortably fit under 10 MB and there are compilation options that can help optimize further [3].
Binaries will be huge tho compared to Go. I’ve a few CLIs that I that I my customers need to use, I’m planning to rewrite them in Go for this reason.