Is there a way to change the fields shown on the Service Appointment list views on the FSL App?

Yes, you can customize the fields shown on Service Appointment list views in the Salesforce Field Service mobile app, but the configuration relies on field sets rather than standard compact layouts. The fields displayed on the service appointment cards within the mobile schedule view are explicitly controlled by a field set named Service Appointments List Columns. To change these fields, navigate to the Object Manager in Salesforce Setup, select the Service Appointment object, open the Field Sets section, and edit this specific field set to add, remove, or rearrange your desired fields. Because mobile screen real estate is limited, only the first few fields in the field set will display on the card before the remaining data is truncated. 

While the field set dictates which fields are visible on the mobile card, the actual criteria for which records appear are controlled by standard Salesforce list view filters. The mobile application maps to these criteria using the developer name of the list view, which must be referenced in your Field Service Mobile Settings under the default list view parameter. This separates the record filtering logic from the physical layout of the fields. After saving your changes in Setup, mobile users must perform a pull-to-refresh on their schedule view, clear cached data in their app settings, or log out and log back in to force a metadata synchronization and see the updated fields.