[MM3-users] finding all memberships for a user using a string match in REST API

I'm trying to return all the memberships for members with email addresses that match a given string. The equivalent of 'mailman findmember jo', which returns 'john@example.com' and lists, 'joe@example.com' and lists, etc.

What I'm doing now is finding users with a string match, then for each user getting their addresses, and then for each address getting memberships. Is there anything more direct? I tried to query memberships using 'user' but I guess that's not supported?