Hello CactusjK:
We use an iPad Pro 12.9 cellular hosting GaiaGPS and we're extremely happy with it. We purchased a unit with the maximum storage to support copious downloading of maps/imagery for offline/out of connection use. We also use GaiaGPS on an iPhone 11 pro (also with maximum memory) and find the syncing of tracks, waypoints & routes between the two helpful. Syncing downloaded maps is a bit cumbersome, especially if you wish to have different resources on the two units, but tracks, waypoints & routes is a breeze. We also have unlimited data plans on both and find downloading maps/aerial imagery via cellular connection much smoother and faster than via WiFi, but that may be due to our horrible internet connection at home.
Personally I prefer a larger screen than the Mini. Another consideration is the rumor that there may be a new Mini coming out later this year.
About the only thing I haven't found for the iPad or iPhone is a good gpx file editor for trimming, joining and cleaning up tracks.
Howard