Yes, I was bunching up Xcode with "Apple ecosystem". I presume you can get clang/gcc without AppleID (but haven't actually done it myself), and for sure many other dev tools.

I'd definitely much prefer if even for "ecosystem" the companies would not require online account except where truly necessary (purchases?), but for operating the OS itself, I do feel there's a line in the sand where online account requirement = no.

Xcode needs an Apple ID for download but the macOS SDK and toolchain does not.

Try to run any developer tool or "xcode-select install" and it'll download the command-line tools independently from Xcode.

(and then bring your own IDE)