Thanks. dottable has only 2 export options: Save to Camera Roll, and Post to Twitter.
However, I've now found that I can keep the transparency via a PNG file through the Camera Roll,
so it does work (I was misunderstanding how dottable did transparency)

I see that Pythonista, has an Edit option for images, but dottable does not appear here, no doubt because it doesn't handle the share interface you mention.

So what do people use that works nicely with Pythonista?

I'm a newbie here.
What do people use to edit sprites.
I've tried the free dottable app, I can create images with a transparent background but can only save them via the photo stream. Loading them in Pythonista means the transparency is lost (due to photos?).

dottable can't save to iCloud drive, and I only have iOS 10 (device too old) so have to access to Files.

What do you use that can import to Pythonista and keeps the transparency?