I would be interested in such an app, too.
I heard back from an app developer that it's possible for an app to fully take over the fan control but not to have it in combination with the system fan controls. It's all or nothing.
They sent me this link on how to do it with their app: https://www.tunabellysoftware.com/support/tgpro_tutorial/#lower_mac_studio_fans_to_minimum
I'm not sure it's worth the trouble though.