I took a crack at this yesterday. I work on a Mac, and this was pretty straightforward on my machine, so I set up this PR: https://github.com/discourse/discourse/pull/10079 however ImageMagick on Linux machines does not come with HEIC support out of the box, so we can’t merge this until we update the base Docker image to include HEIC support.
I’ll work on that now, but this will take a bit longer to get to core.