I love the "Assignee" permissions where someone can only see records that they are assigned to - however I'd love to be able to use a lookup field for this.

As an example:

I have a table called "Projects" that has a field called "Members" - where I can assign specific people. When I use the Assignee permissions that works great - I can ensure only the members have access to their projects.

However - let's say I now have a "Tasks" table - each task is linked back to a project. I have a Lookup field in Tasks that lets me see the "Project Members" for each task. I have a filter that allows me to ensure the user can also only see the tasks for a project that they are assigned to - but I can't select the Assignee field if it's a lookup field in permissions, so it's still possible for that filter to be removed.