Hi Jules
I am also using a MacBook Pro with touch bar (after my old mac laptop started to die with almost 9 years). PixInsight so far has no special support for touch bar and I would not expect this to show up quickly for the following reasons:
* There is a very small user base using Macs, in particular Macs with touch bar.
* For programs like PixInsight, the touch bar simply has not enough space to be of much use. To many buttons and sliders to choose from!
* A touch bar for Linux or Windows users is unlikely to show up in the near future.
On the other hand, the touch bar can help to make some functions more easily accessible. A good example is the Terminal application: one can display man pages for commands typed in the console easily. In general, some context menu items can benefit from the touch bar most.
There are, however, alternate ways to get touch bar functionality in applications without touch bar support! I googled around and found BetterTouchTool. I downloaded the trial and consider buying it if it works well with PixInsight.
From my experience, the touch bar is not a complete success, because it takes away the escape key and function keys (simulated touch keys are not a valid replacement for real keys) and creates a niche input device, but the bar has its valid uses. Maybe in the future, Apple will sell laptops with both: function keys and touch bar, and also external keyboards with both. Then, even Linux and Windows users could use those external keyboards.
Best, Peter