Changing the UI from swing to the more modern JavaFX UI technology for just the initial game launcher screens has so far been a multi-year project and is not complete.
True, but to be fair most of the time there wasn't any active development on this, simply because it was and still is a tedious process to decouple all of the logic and not very fun at all. Which is the reason most of us are developing TripleA I think. At least that's the case for me.
However I have plans to continue developing the UI starting next month, hopefully to a point where the game can be launched at least in single player anytime soon.
Once it is playable using the JavaFX UI (which will wrap Swing components for now), which might be feasible this year if I have the time and motivation, I hope that we will all stop adding swing components, but instead go for JavaFX exclusively so that eventually there won't be any swing components left.
But @LaFayette is right, for now any "simple port" solution would be the easiest and fastest way to achieve something like this.
The barrier is that most logic is in the UI layer, the two are interleaved
Plus, what makes this really hard to deal with is that this is noticeable across the entire codebase. You can't just migrate classes step by step, instead you have to sort-of-migrate a part and create an exception for non-migrated parts that are still using UI directly.
Also, Teamviewer is $50 a month for a personal account.
Only for commercial purposes. If you're using it just for yourself it's free. Obviously this isn't a general solution but if it works for you when you have a PC somewhere running TripleA that might be a fast solution as well.