Zen has quite a nice array of keybinds available in their basic settings menu. Just had a conflict of ctrl+shift+l opening some dev tools window instead of BitWarden, and the browser hotkey was easy to change. Speaking of keyboards, Tridactyl (https://docs.zen-browser.app/faq#how-can-i-sync-my-data-acro...) works out of the box in Zen as well

Better than the default, but not a nice one - the basics of tab navigation (previous/next) are missing, and you can't assign multiple shortcuts to a command.

And extensions don't cover it since they fail outside of a webpage context, so if you have a key to change tabs, you can't just (reliably) use it - it will break your changing sequence once you switch to a protected Settings tab