Update: Implemented! Thank you Esri.
Doc: https://doc.arcgis.com/en/field-maps/latest/prepare-maps/configure-the-map.htm#ESRI_SECTION2_D4A1D89377A3411C8CA25C49F1C28187
Real-World Problem: Urban Search and Rescue (US&R) Task Forces need to be able to collaborate with other teams sharing one common map. However there are times when they want to see just the data collected by their own Task Force or by a certain date.
Technical Problem: There is no way for the end user to filter Field Maps. This means the map author needs to create separate feature layer views for every possible scenario (impossible).
Solution: Allow the Field Map author to setup predesignated filter options like you can in Web AppBuilder or Experience Builder. Then the end-user should be able to just click on a filter button and choose how to filter (eg Date, Team, User, etc). It could just be a option in the tools dropdown.

@JeffShaner