Kupfer is quite useful without extra plug-ins. However, when a service you use is not provided, it becomes quite hard (or impossible) to work with it without a plug-in. To write a plug-in for Kupfer does not need to be difficult as there is a lot of functionality provided for first time plug-in writers.
→ frenck.dev/diy-smart-doorbell-for-just-2-dollar
This article is going to show you how to convert your (existing) wired doorbell (also works for battery-powered chimes) into a smart, WiFi-enabled, doorbell. The essential components needed sets you back about $2, yes, that is correct, just two bucks. No soldering is required and you don’t have to be an electronics expert.