There is a new app on Play Store - Obsess for Ghost which I have just tried. It seemed to work OK but I’ve only tried a couple of simple test posts so far.
Hopefully it will be a good unofficial alternative.
BTW I also discovered that you can simply edit using the normal webpage in your browser on Android. If you try to create a post you can enter text but the little + icon to allow photos/HTML etc doesn’t appear, so at first you might think you are restricted to text only. However if you change your browser settings to “Desktop Site” then that + icon appears ( you may need to swipe left slightly) and you can add rich content. Desktop mode is not tremendously convenient so I enter text in normal mode, switch to Desktop to add a picture and then back to normal to continue with the next paragraph of text. Not tremendously convenient but it works.