The internal tools at Meta are incredible tbh. There’s an ecosystem of well-designed internal tools that talk to each other. That was my favorite part of working there.
A friend of mine is doing his PHD while being an intern at Meta. He does not share your excitement... at all. To summarize his complaints: a framework written a long while ago with design flaws that were cast in stone, that requires exorbitant effort to accomplish simple things (under the pretense of global integration that usually isn't needed, but even if was needed, would still not work).
fork open source, then demand resources to maintian this monster.
easiest promotion + job security.
its even called "Platform Engineering" these days