A friend of mine founded a company in this space (https://www.joincake.com/). From what I know it is more on the side of helping you build your own solution, rather than delivering all of the technical aspects.

The technical integration would be some significant effort to work out: do you need to run a credential management service? Can you get away with just having account recovery codes, specifying beneficiaries for specific accounts, etc? At first glance it feels like a massive amount of integration work would be needed