The ability to use Linked Fields to dynamically filter another Linked Field is excellent.
Often however, we need the same functionality for a Linked Field but where the Dynamic Filter check is made against a Single (or Multi) select field.
For example, in 3 Apps, App 2 and 3 would have parent/child records, that both have a Single Select field.
App 1 would also have a Single Select field, and a link to both other Apps. The Single Select field designated in App 1 record, then limits the selection of the Linked Fields for App 2 and App 3.
It's a little difficult to explain - but think of the dynamic filter functionality that's recently been developed, but instead of using Linked Records in the filter, we may also use Single / Multi-Select - oh, and importantly, with the ability to cross-over their usage. So for instance, a Linked Field condition (text) can be checked against a dynamic Single Select (text).