と思ってたけど、左の画面内ギリギリでちょっと長く触れてからスワイプすると戻る機能が働かずメニューを出せることが今調べて分かった
https://wiki.termux.com/wiki/User_Interface
> The navigation drawer is revealed by swiping inwards from the left part of the screen (if you have gesture navigation enabled in Android, you will need to hold briefly on the edge of the screen before swiping to bring up the navigation drawer instead of going back in Android).