Since a few folks seem unaware of this, I’m posting anew for visibility.
The choice gesture vs. nav button is usually part of android itself. In my case (pixel with therefor nearly stock android) its in settings -> system -> navigation mode (or something similar since its in german in my case). If you can’t find it, search for “navigation button your phone model”.
Edit: sorry, i just realized you meant the app drawer, not the overview of currently opened apps. I don’t know the answer to that.
Edit edit: ok i found something in lawnchairs settings. The last setting is called gestures. If you have navigation buttons enabled instead of nav gestures (see above) you could bind the home button to open the app drawer.