Ok. You mentioned the iPad Mini for using follow mode which is why I commented. As you stated they don’t work with DJI Fly app which is due to how old they are so it may be why it won’t work with Litchi as well. Maybe Litchi can answer that question.
Most iPads do not have GPS capabilities. They only do if you have an iPad version that also has cellular functionality. WiFi-only iPads do provide location services that do not rely on GPS. To do so, they use WiFi or tethered devices to obtain very rough positioning. This non-GPS positioning is not sufficient to provide “Follow Me” capabilities.