ReadOut Entity status (BOOL) and collect to a bitrow, and send a push notification

I have e.g. Homematic devices, where i have a LowBat message.
To collect all devices to one group, i need a kind of WORD, to collect all datas, and show it in a entity on the dashboard, which Bit is TRUE, to show me which device battery is empty.
And additional, i want to make a push notification, that one of the batteries is empty.

From workflow it would be:
1.) Message that at least one battery is empty (extended version would be: text me, which device battery ist emtpy
2.) Show me in a collected entity, which Homematic device is empty.

Can anybody help me?

I want to do this with Node-Red, to have a better overview.