Can you make an option to upload georeferenced charts into SD just like in ForeFlight?

I am sorry to hear that! It may not have been mentioned often, but it would solve some shortcomings.

If the custom data airfields simply would get a Plate ID to its ICAO code in the Plates index.xml and the possibility to add a PDF with your simple ReferencePoint mechanics it would be all needed - it would be 'just another airfield as any other'. GeoRef'ing in Skydemon does not look particularly complicated on the PC in the end, see the quick GoogleEarth overlay shot below:

(For the PC tinkerer: pull C:\Users\<user>\AppData\Roaming\Divelements Limited\SkyDemon Plan\Plates\index.xml, look for the PlateID of the airfield, understand the georeferencing by the readable definition of the box on the pdf and some reference points, change the <PlateID>.pdf to whatever you want, save. Yes, I know there are some functions to do as well to add custom data this way, but why not add a country = customlands ?)