I don’t know why Apple insists on sticking with HEIC when so many platforms still have trouble with it. Anyway, after struggling to open them on my Windows PC, I ended up using a heic web converter that runs right in the browser. No install, just drag the file and download a JPG. It saved me from downloading sketchy apps or messing with codecs. I use it now whenever I need to pull images off my phone and send them to people who don’t use iOS. It’s quick, safe, and doesn’t mess with image quality at all. Wish I found it sooner, honestly.