Hi Bruno,
FWIW, on 15.2 it works with a Prime X570-P and this setup:
kasi@mars:~/Downloads> zypper se -i openrgb
Repository-Daten werden geladen...
Installierte Pakete werden gelesen...
S | Name | Summary | Type
---+-------------------------+----------------------------------+------
i+ | OpenRGB | Open source RGB lighting control | Paket
i+ | i2c-openrgb-kmp | I2C patches for OpenRGB | Paket
i+ | i2c-openrgb-kmp-default | I2C patches for OpenRGB | Paket
kasi@mars:~/Downloads>
Unfortunately, the patches ic2-openrgb-kmp* don’t seem to be available on 15.3, yet:
https://software.opensuse.org/package/i2c-openrgb-kmp
Maybe try and contact the package maintainer on OBS?