Tenways was mentioned earlier and even if it's a bit heavier than what you're after (14 kg something i believe) I can recommend it (have their first model). Single speed, beltway drive makes it maintenance easy. Just wipe it of with a damp cloth.
I was hoping to recieve some help with the app. I recently bought a Merida eSilex which have the Mahle X35. Unfortunately it had a faulty battery which got replaced at the bike store. Before I returned it I could connect the app with the bike and access the eBike options with all its features...
