I just made a multiresolution tour with krpano tools 1.20.9 using vtour-multires.config. In tour.xml I include vtourskin_design_ultra_light.xml.
In other words, everything is stock krpano latest release.

Using krpano testing server, everything looks fine on PC bowsers, including 'fake VR' mode in response to VR button. This is true both on the machine hosting testing server and other PC or Mac on the same LAN; but when I load the tour in a phone or Oculus Go via the LAN there are no zoom, pan, or VR buttons on the control bar. Buttons for fullscreen, thumbs, hide/show bar and next/prev pano are present and work as expected.

What must I do to get those missing buttons on mobile and headset?

I fear that this might have something to do with the lack of https support by testing server, but I hope that is not the case as I intend to host these tours on AWS S3, which also does not support https.