I was trying to find the exact post where the Framework team explains the rationale, but can’t pin it down. At any rate, for now, you use Framework’s own fork of the VIA software to configure with their fork of the firmware:
A community member also made a fork of the firmware that supports OpenRGB, if that’s your preference:
Someone from the FW team will have to chime in and remind us of the reasons this isn’t merged upstream yet.