I'm so sorry to be a pain in the ass, but both options don't work for me :(
With BPH.app it just won't open (whether I put it in Applications or just open it straight away) and BPH.zip I unzipped and opened Contents/MacOS/Backpack Hero, but it just opens a text document with code. I will keep helping you with testing if necessary. Furthermore, I really appreciate you trying to make this work. I unfortunately don't use Steam, so that's why I'm asking for your help on the files on Itch.io.