Custom Claim Providers and SharePoint Online

Hello everybody.

I'm facing a customer request based on the re-using of custom claims provider on SharePoint Online. They've Sp2016 Hybrid, and they want to create an online SiteCollection where to store documents (integrated with Dynamics AX on 365 platform) and to base permissions on the claims structure they defined already in the onprem implementation with another partner. Using SP Groups is not an option due the depth of their organization and roles.

Is that possible? Custom Claims are Farm scoped, from what i know.

Thank you,

Michele