I got it to build and install on the rpi3b, and connected okay, with new buttons showing for align, which is pretty much as you describe in the status, goto, center, sync. Folks can also align using the plate solving and center/sync in Kstars or skychart, which is how I've been doing it once the times and places are matching.
The unpark now sets the motors in motion! It's still a bit glitchy, having to click park before you can unpark, and you might add the button calling the "set park position", go home and set home routines to your todo list for later polishing work too.
GPS coords error: The reported position from the mount is "correct" but looks bizzare --> 279:48:04 = -80:48:04 and while Kstars is showing the proper position for objects, goto's are claiming below horizon when I try to goto.
I did some more testing and now think the horizon errors may be due to times not being synced properly. I have kstars set to update the mount but was unable to goto until I set time via the phone app.I did a short hop to nearby kocab and it took it, and then I was able to use the goto. a bit weird. I'll do more testing on that. I don't have an RTC board on this new setup so time syncing may be important.
You might want to add "update tracking frequency" to the bottom of your todo list. It works fine after you poke the set button but isn't getting the original info from the mount.
Also add to that list to (if possible) increase the upper limit above 60.1hz to something like 62hz to give us more headroom when tuning for gear ratio discrepancies. I noticed that poking "sidereal" is already setting frequency above that point, and comes very close to matching on my mount but due to the above problem, isn't set at startup.
This is less of an issue than the init. and speed control but I thought it worth mentioning for later.
I tried to test using Skychart but ran into a few nasty bugs. I think Pascal doesn't grok Xubuntu very well.
Anyhow things are moving forward. A good days work!