You can go to the trouble to learn Rust, and then fight with them to get your modifications accepted or...
Can you actually point to any instances of the devs dragging their feet on accepting changes or is this just conjecture? I've contributed to Lemmy, and plan to do so in future, and my experience is that they're fairly accepting of changes.
An elected HoL would probably require a referendum, something we're all a bit burnt out on, so this probably isn't going to go anywhere.