Looks like Firefox is adding a new group policy item AIControls that directly matches the "AI options" settings page: https://searchfox.org/firefox-main/rev/34fc93ba6c4d8f57cd154677f0c4cd9907fd1339/browser/components/enterprisepolicies/Policies.sys.mjs#114 (this was commited a few days ago and is not yet in the templates)

This will have priority over the existing-and-probably-to-be-deprecated GenerativeAI policy group (FF144), and will hopefully reduce the need for AI-whack-a-mole with Preferences JSON.

FF148 also added a DisableRemoteImprovements item that you might want to think about.