ld -z now,
When generating an executable or shared library, mark it to tell the dynamic linker to resolve all symbols when the program is started, or when the shared library is loaded by dlopen, instead of deferring function call resolution to the point when the function is first called.
ld -z relro,
Create an ELF “PT_GNU_RELRO” segment header in the object. This specifies a memory segment that should be made read-only after relocation, if supported. Specifying common-page-size smaller tha the system page size will render this protection ineffective.
also some additional useful info can be found here https://wiki.debian.org/Hardening
librewolf don’t remove any “proprietary software contained within” it’s just
firefox with changed default settings and icons
here is sources and you can see it yourself, and not just misinformed people
you can try to install alpine-pkg-glibc