[fsiegert]

Will these cores work on Raspberry PI 3?

I've only tested them on LibreElec running on an RPi. If you're running some other flavor, maybe? I'm not sure.
You could try the repository listed in the read me here, or you could try manually downloading one of the addon zips from here and installing from zip in Kodi.

Just for reference, in case it's still relevant: I have tested the armhf repository on a Raspberry Pi 4 running Raspberry Pi OS (previously known as Raspbian), and it seems to work fine so far. So I guess you could expand the README to more than just LibreElec.

Thanks for providing this!