The idea of using 'dead' keys is based on assumption that pressing 2 easy keys is better than pressing 1 hard key. So to make it easier to type (programming) characters/symbols, we're going to press an easily reachable key (which will NOT output any character), release it and then press another easily reachable key to produce, say, @ character.
In this layout the COMMA key is a dead key, pressing it will cause keyboard enter a state in which a single stroke of other keys will output a different character than normal state. After that single stroke, the keyboard returns to its normal state.
For example, you'd press COMMA to enter the special state. Now if you strike the A key the output will be a forward slash "/". To see how to create other characters, refer to following images for more info.
To produce the COMMA character itself, just hit SPACE after entering 'dead' state.
I'd like to achieve this functionality on Lubuntu (19.04) too, but I don't even know where to start... or if something like this is even possible. Could you please give me some pointers?