I'm in the process of building a personal set, which I'll share in various stages as I'm able.

One interesting thing to note about the way Dorico currently does expressions is that it's pretty easy to simply build them as you need them for each project.  Things will improve as they eventually give us the ability to make user techniques that we can drop into the score, and I suspect that they'll eventually give us a much more robust "Play" tab with controller lanes and such as well.

Meanwhile, have a look at this thread for short guide on getting ARIA Loaded and getting a start making your own maps:

https://www.steinberg.net/forums/viewtopic.php?f=246&t=113796&hilit=GPO

Brian, I wondered how you're getting on with building GPO Ex maps for Dorico? 

I'm currently fine-tuning my own set, based on your Schubert example, and the Steinberg set for Cubase. In the absence of anything better, I'll post them on the Steinberg forum soon. 

I've completed my 'basic' set of Expression Maps, which also includes documentation of what I've done, and what you might like to do with them. Also a spreadsheet of keyswitches, CCs and instruments.

They can be found here:

https://www.steinberg.net/forums/viewtopic.php?f=246&t=201477