It sort of depends what you want to use an app for. To just know that it is charging and when it is done, a lot of apps like Chargepoint can do that. The other useful functions are an estimate on when it will be done charging and the rate KwH wise it is drawing power. The other is to set the climate control on/off when away from the car. Useful for hot days and cold days.
I would like to believe that MB is indeed transitioning to a new app as someone suggested. To leave us in the lurch would be pretty stupid as current MB customers and future EQC buyers.
BTW, bclassupstate, welcome, enjoy the ride.