Yes, the AI service can be set up on either a Fidelity Cash Management Account or on a Cash Manager funding account. Note: AI service is currently only available from an outside account to a Fidelity account.
If you want a funding account to have the AI account feature, you must establish AI on the account before linking it to the Fidelity Cash Management Account via Cash Manager. If an account is already linked as a funding account, and you want to add AI, you must first de-link the account, add in the AI, and then re-link the account to the Fidelity Cash Management Account via Cash Manager.