Would it be difficult to make an app for iPad or iPhone that has digital versions of trim wheels for elevator, aileron, and rudder trim? I wouldn’t know where to start; just wondering if anyone has done this.
Try Touch Portal it is available on Android and iPad. You will then need to either create your own or download a config that some one else has done. See the pictures in the post by Stona, there are also links on those pages to what you need.