I have an old Magellan Meridian Plus and it uses positive numbers. I've got a GPS in our 2008 Prius and it uses positive numbers for input.

I looked at my iPhone (11) and none of the three map apps had an option for longitude/latitude entry. They all expect you to use a 'street' style map or to use landmarks to locate spots I guess.

This is making me think I need to do some serious research on this as it never occurred to me that putting in this information would be problematic.