Comment by notpublic

Indeed! I just found out about tmux display-popup recently.

  # ~/.tmux.conf 
  bind-key C-g display-popup -E -d "#{pane_current_path}" -xC -yC -w 80% -h 75% "lazygit"

Then, in tmux:

  ctrl-b ctrl-g will open a popup window with lazygit
  q to quit