jj or qq can also be used. As I once started with GNU Screen ages ago, I like prefix to ctrl+a but it interferes with going to front of command in bash mode. For that, I use vi keybind mode in my shell (fish or bash) which feel very natural to me. For zellij, I use default prefix so that it does not interfere with remote (yes I am aware remote requires double prefix; I prefer using tmux remotely and zellij locally).

How are you configuring jj without interfering with using the key regularly? I used to have jj bound to ESC in VIM, loved it, but I've since trimmed back my config as I SSH into to many foreign systems to depend upon nonstandard behaviour. But I'd love to have it in Tmux.

The obvious `set -g prefix jj` throws an error that the key j is a bad key. Various experimenting with bind and unbind have not resulted in success, and I can't seem to find an example .tmux.conf with that config to copy.

I second this. I wouldn't have been able to make tmux such an integral part of my daily workflow if it weren't for this binding that I came across in someone's starter tmux conf many years ago.