If I can add my request to this thread: the carillon.
The carillon is often a transposing instrument (with instruments existing in many different keys) written with a grand staff, which is the main reason for the request (there’s no transposing instrument in grand staff currently).
My mother (also a Dorico user, but not a power-user) plays a carillon in F, and uses piano as the instrument in Dorico.
But when she plays with other people / instruments, mistakes with transpositions can happen (because she manually transposes the piano part).
There’s a workaround of course: use an instrument like Horn in F, add a staff, hide out-of-range notes, and change the used samples in Play (there’s no carillon sample, but piano suffices).
You’ll discover many intricacies with the carillon (e.g. often the lowest notes are a B flat and C natural, with the B natural missing), but I hope this instrument can find its way into Dorico sometime!