Months after the iOS release, with the new redesigned version of the Gmail app. Now, on the latest Gmail update (v2019.08.18), a new swipeable account switching gesture is possible. All you have to do is either swipe up or down on your user profile picture in the top right corner of the Gmail search bar. With this you can switch accounts quickly and much easier.
Also there are a few smaller hints towards the long awaited dark mode. If you are running Android 10 beta and enable system wide dark mode, the Gmail app will display a dark splash screen, but turn white when finished loading. This likely means the implementation is there, but not completely ready. We expect to see this released along side the public release of Android 10.
The latest Gmail update is in progress of rolling out over the next few weeks, so it could be a few days before you see it. You can download Gmail from the Play Store via the link below.