From Past experience.  Can anyone say how long it  takes  a device to go from initial release
to being on the approved list? It seems the latest devices are no where to be seen on the approved list.

DJI doesn't add new mobile devices often. While that means they only support a limited number of mobile devices, that doesn't mean those are the only mobile devices that will work.

This list shows many other mobile devices that DJI drone owners are successfully using:

Best Tablets and Phones for DJI GO (Updated Daily)

Hi, thanks for the inquiry. As of the time being, our team hasn't cascaded to us if there will be an additional device that would support the official DJI GO 4 app. Due to a lot of devices that were released in the market, our team can't be able to test them all to determine the compatibility. However, you may provide us your preferred device and we will forward it into our designated department to see if they could test it for the compatiblity matter. Thank you for understanding.

Has anyone used the honor View 20 with the app?

djiuser_KUkNn8m4G6J1 Posted at 4-22 23:54
Has anyone used the honor View 20 with the app?

Hi, thanks for the inquiry. We're hoping that you could get the best feedback from our valued DJI Forum members who uses the same mobile device that you've mentioned. You may refer to the image below for our compatible devices with our DJI Spark. Thank you for your support.