WTF, Adobe?!? How come Photoshop still can't open HEIF files when so many devices write them? I am used to you ignoring your Premiere Pro users (of which I am one), since the ones that stuck with it until now just don't have any alternative (Resolve is good but has its own issues), but GIMP is an excellent (and completely free) replacement for Photoshop, which supports HEIF files (among many other things they got over PS), so I would jump ship over this in a heartbeat.
This codec doesn't work. I just downloaded it and it installs automatically on a Windows 10 PC. Photoshop will still not open an .heic file. Read the reviews for the codec, people overwhelmingly not the same thing in their reviews, the codec doesn't work. So, this is not the "correct answer".