It is extremely hard to create an application that doesn't depend on CRT on Windows. CRT provides tables for handlers of SEH exceptions and provides the default event handlers. Win32 headers have hard dependencies of the handler tables CRT provides. So you need to go quite a bit out of your way to hack deep Win32 headers. Loading DLLs etc also may call CRT functions.
You can read Mingw64 source to see how many hacks they had to do to make it work.
That's the "vcruntime" not the "ucrt". There has been a distinction since the ucrt was made an official part of the OS.
It's very easy to make a win32 program without the ucrt filesytems APIs so long as you don't mind being platform-specific (or making your own cross-platform wrappers).
I have been developing for Microsoft platforms since MS-DOS 3.3, Win16 and Win32 development without any function from standard C library has been a thing for decades, for those doing C development without caring about portability, like demoscene competitions and gaming.
You can read Mingw64 source to see how many hacks they had to do to make it work.