I have just connected the Rode Wireless Go II to my Fairphone 3. Normally, the recording apps do not accept an external microphone. But thanks to Open Camera it works perfectly, and this is still a free app. Simply set it to external microphone under Settings->Video Settings->Audio Source and it works.
Here you find more information about connecting and settings from Open Camera, in german: Filmen mit Kameraapps auf Android-Handys - Matthias Süßen