Would it be possible to do sort of 2 selectors on the start side to choose the main wad (like doom 2) and another selector for the addon wad? That would make it perfect and more comfortable to use on the go.
The short answer is no, sadly
If the underlying wad being used and the modded wad name were the only things needed then it would be no problem and could probably work exactly as you describe. Unfortunately some conversions have multiple wads and some also need a dehacked file.
At least by using command line options we also get the advantage of the extra features like auto-loading a save game slot on launch etc..
I've tested quite a bit and so far the Dingoo port is behaving exactly like the windows version of Chocolate Doom. If you have all your wads in the main folder on the PC or Dingoo then the -iwad command line option has to be used to specify the official wad needed. I quite like the simplicity of throwing everything in one folder so I've decided to leave it like this.
Version 1.2 is only different by one line of code which is a bit crap really!
It changes how the save game folder is created and now does this using the name of the .wad or .txt file used to launch the game. This means you get a full amount of save slots for each game and don't have to share with the underlying wad. Be sure to move your saves for the official wads if you've created any as the folder name is slightly different for these too now!
There are lots of little things that could potentially be added still and I would like to come back to it in the future to have a go at midi support for the modded music but for now, aside from any new bugs cropping up, I will probably call it a day.
Thanks to everyone for your feedback and support!