In my experience, you need the app if you use a valved filter (i.e. Clever Dripper) as being a little cooler, the Ember mug doesn't trigger the heating, and you have to tell the app to increase the temperature manually until it realises there's a hot drink in there.

I use these phone holders; cheap, sturdy, easy to tighten and fold down: https://www.amazon.co.uk/dp/B0BP1ZQTJ1