That’s what I was doing myself (first “AddLinkedLibs” and then loading an almost “dummy.cxx++” script which used anything from my library, so that the linker was “forced” to take it, but you may also need to play with “-Wl,-whole-archive” or its equivalent on OSX).
But I think a better solution is to re-link your archive library into a shared one (like you do it in your first post above). I guess you could try to simplify this step: g++ -std=c++11 -shared -o libabsl_strings.so -Wl,-whole-archive libabsl_strings.a