The fundamental issue is that . Windows uses the Portable Executable (PE) format with x86/x64 machine code, while iOS uses the Mach-O format with ARM64 architecture. A direct converter would need to rewrite the application from scratch.
To understand why you cannot convert an EXE to an IPA, you must understand what these files actually are. Comparing an EXE to an IPA is like comparing a diesel engine to an electric battery. They serve the same purpose (moving a vehicle/power), but they are not interchangeable. exe to ipa converter