For all the generated code, ReadOnlySpan<char> and MemoryExtensions.Equals can be found on System.Memory.

The only thing missing is the implicit conversion, but calling AsSpan() for those targets solves it. I'd go the extra mile on special targeting this, as the runtimes that provide implicit conversion might improve on int. At least, we avoid the null check.

For the fallback, well, those users already needed to convert it to a string, so, no loss here.