

Well that’s how you make a polygon in iD.
You don’t actually need perfect geometry on your first pass of an area like this. There is basically no existing data, so you aren’t damaging good data. You can add a massive overlapping polygon which gets cleaned up over time.

OsmAnd is not OpenStreetMap. Its a third party client to the OpenStreetMap data.
OsmAnd can have aerial imagery, Configure Map > Map Source ( > Add More ) > Microsoft Hybrid