the reason the new gestures aren't working for some people is that up until the newest patch of Android 10 which so far is only available on the Pixel 4 (the newest One UI 2 beta patch is behind) the new gesture system is only able to be used with stock launchers due to the way it's built being integrated into the launcher. if the option is unavailable in settings for you it's because you're using a 3rd party launcher. the only reason we were able to use the new gestures with 3rd party launchers on the last patch was due to a (possibility security impacting) bug which was cleared up in the current One UI 2 beta patch. Google has promised that the patch allowing 3rd party launchers to use the new gestures will be coming to other phones other than the Pixel 4 "eventually" so just hold tight i guess.
