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https://github.com/KrisKennaway/ii-pix/ converts to Apple II Hi-Res, Double Hi-Res, and 320x200 Super Hi-Res (disclaimer: I'm the author)

I went the opposite direction: convert C-64 files from "Doodle" format to IBM EGA format https://www.kmoser.com/sourcecode/VIEWC64.MOD

Check out Dithertron, it’s got Apple ][ (and >30 other platforms): https://8bitworkshop.com/dithertron/