Try this in your tmux.conf:

    bind -T root M-h select-pane -L

(I’m typing this from my phone from memory, so bear with me if there are minor mistakes.)

The -T root does what you want, ie bind a key without a prefix. M-h is Alt-h, so change that to whatever you want of course.

I am a heavy Vim and tmux user, so if you’d like you can use my own config for inspiration:

https://git.sr.ht/~gpanders/dotfiles/tree/master/item/.confi...