Not sure what you mean. I am very familiar with the transaction script engine, difficulty adjustment algorithm and the p2p protocol, veracks, banscores, persistent peers. I forked the btcd codebase to match an ancient 2014 chain.

And core devs don't control anything. Plenty of other inputs you can see on the issues and the linux.org mailing list.

Bitcoin is a common property so it cannot be changed without very long discussions. Go look at the BIP list, now nearing 300. Much of the new stuff not yet implemented.