How to monitor/track unavailable devices

I ended up using package, i think it’s THIS ONE. Works great, althoug now i see that i have outdated version (author did quite some changes from back then). But it works perfect. I ended up using original version - all unavailable entities are shown except ignored ones. Using it reversed is - well, a bit “dangerous” since it’s very easy to forget to add new sensos/device and you don’t have a control over it.