You can completely skip all CRTs on Windows and still have a program that can call dynamic loader and other Win32 APIs. Here is a tutorial: https://nullprogram.com/blog/2023/02/15/
When you link with UCRT your specific program just gets a "view" of standard C functions. You can load DLLs that were linked with MSVCRT from a UCRT program. It just works
That's a pretty great article. Re. the stack probes, it's not hard to supply your own; Raymond Chen recently did a blog series on stack probes, the entries for amd64 and arm64 are here:
When you link with UCRT your specific program just gets a "view" of standard C functions. You can load DLLs that were linked with MSVCRT from a UCRT program. It just works