@thelastpsion musl is a great libc, perfect for static linking. If you want "build-once run-everywhere", there is a cool project called Cosmopolitan (https://github.com/jart/cosmopolitan), but I never used it so I can't say much.
GitHub - jart/cosmopolitan: build-once run-anywhere c library
build-once run-anywhere c library. Contribute to jart/cosmopolitan development by creating an account on GitHub.