Definitely agree. I was able to convert Town of Passion to a Mac version, but with the new RPGM version he's using to make KoP, conversion is a little less cut-and-dry. Hoping for an official version soon!
So, to do this you'll need to download an RPG Maker game that's compatible with Mac. Then you can use that game file as a 'shell' to convert Windows versions of RPGM games (like this one). Here are the steps you'll need to take:
1. Download a Mac version of an RPG Maker game. Pretty sure most RPGM games like this use the MV engine. You can search here on itch and filter to only show Mac games, and select the tag for RPG Maker MV.
2. Extract the file and you'll usually see a folder with a file called 'Game.' The file may be called something different, but whatever it is, find the actual game file.
3. Rename that Game file 'Kingdom of Passion' or whatever you want, then right-click, Show Package Contents.
4. Navigate to Contents > Resources > app.nw. Erase everything in that folder.
5. If you haven't already, download the latest Windows version of Kingdom of Passion and unzip the file.
6. In the extracted files, navigate and find the 'www' folder.
7. Select everything in that 'www' folder, and copy it to the 'app.nw' folder.
And that's it. Open up the game file you renamed and it should run normally. I tried this with KoP and an RPG Maker MV file and it's been working pretty nicely. I originally thought that Siren had used an updated version of RPGM (the MZ version), but I think he's still using MV.
You can keep a copy of that empty Game file to create a Mac version of any RPGM MV game. I've done it with plenty and it usually works without too many glitches.