I do not want to have to move my eyes away from the tablet screen in order to execute whatever the Back button executes on my tablet. This should be as about as quick as using a desktop browser's ALT-BACK-ARROW, but on the tablet, and should do exactly what that back button does.
I just upgraded from a Samsung Galaxy Note 10.1 (not the 2014 version, this is the old original version) to a Samsung Galaxy Tab S3 (not the same as the Samsung Galaxy S III (GT-i9300)). On the old Samsung Galaxy Note 10.1, I could hold the S-pen side button, and use a "less than sign" gesture as shown in the screenshot below as a "Back Button":
I want to know if there is some way to re-enable that very useful (to me) feature as it saves a lot of time when doing research since the Back button is a high-frequency operation.
Installing additional free (or less than 10 USD) apps is an option.
The solution does not have to use the S-pen, but it has to be demonstrably faster than moving the S-pen over to the side of the tablet to click the Back button. Yes, I've tried various things that actually don't work (various combinations of holding side buttons down which in and of itself is even worse than the button on the tablet).