I watched a Youtube video and briefly saw Captain Vanouver play an FPV drone simulator on his phone while waiting ("Winning a Drone Race with Captain Vanover!", @10:56). That got me into googling for fpv simulators for the phone (i found FPV Freerider), and then how to connect my PS3 controller to my phone and THEN how to rig my GearVR headset to work with the game. I had most problems getting the GearVR to work, because when connecting your phone to it the GearVR app automatically launches on your phone.
But here is how I got all to work:
Controller
Using an OTG adapter (USB A to C) and an USB mini-cable I could connect my old PlayStation 3 controller to my Samsung S10. After a few seconds it was connected successfully. To get the controller to work in Freerider I enabled "USB Controller" as input, enabled "Throttle zero at center" and then calibrated the controller in the app.
Samsung GearVR
To disable the Oculus/GearVR app from auto-launching I had to download "Package Disabler Pro", version 15.2. Once installed I searched for "Gear VR Service" and enabled the block of that app. Inside Freerider app I went to "Custom Settings" and enabled "Side-by-side view" and disabled "Stereoscopic SBS FPV" (because it made the screens out of sync for me).
That's it! I can now train on flying in acro mode while waiting for my drone, controller, real goggles etc arrives from Banggood. :-)