I agree. I would love a standalone app (Mac, iOS) which did not require offline access, even if it was multiple gigabytes. There was an old OED 2e app for the Mac with the full content.
The standalone offline concise version includes updates, has 1/3 of the OED and is 128MB on iOS.
I just published a repository that de-obfuscates the archive from OED's Windows CD-ROM version. I don't know anything about the markup language it uses and I don't know anything about JSON either, but I attempt to parse it and convert it to JSON.
Sadly, the archive only contains 300,000 words IIRC.