Detecting 2 different 120 Volts AC sources

Hardware
1

In my zone power is failing frequently and I had been solving the issue with an inverter generator and a manual transfer switch.
However, I don’t have a means to know when power comes back.

My plan is simple: energize a WeMos D1 Mini from the line that will always have power (regardless of the position of the transfer switch) and energize the 2 relays, one from the mains and another from the power generator. Then connect a DC line output from the WeMos, in series across both relays snd returning to the WeMos. It there’s continuity, then it means that both relays are energized.

I can program this WeMos with ESPHome as a sensor to tell me that I need to turn off the power generator.

My question to this group is, what are the cheapest, lowest consumption relays or equivalent devices that I should be using for this? I found this:

Tnisesm 2PCS Power Relay SPST(1 NO) AC120V Coil, 30A SPST 120 VAC with Flange Mounting and 8 Quick Connect Terminals Wires Mini Relay HF105F-4-AC120V-8X https://www.amazon.com/dp/B087G3FWVT/ref=cm_sw_r_apan_glt_i_511WK5JF8ER9Z1FYK8NZ?_encoding=UTF8&psc=1

But it doesn’t mention how much power does the coil consume.

This other one specifies, but doesn’t include the cables:
American Zettler Power Relay, SPDT, 30A, 115v, Mini, 30A SPDT 120VAC AZ2280-1C-120A( Pack of 2) https://www.amazon.com/dp/B07587NZTC/ref=cm_sw_r_apan_glt_i_EDY24QGQEYA1NDRB1M1F?_encoding=UTF8&psc=1

I already have the WeMos laying around, but another question is do you have a simpler way to solve this problem?

2

Thinking out loud, but wouldn’t a CT Clamp on the mains an easier possibility?

EDIT: Actually, wouldn’t the absolute easiest be to hook to Wemo to the mains and pinging it for availability?

3

Using a Wemos on each side and adding some logic that reacts if both at alive should be better, yes. I guess that I’ll need another 5v USB power supply and cable (I have the 2nd WeMos D1 Mini laying around). I’ll also need AC female plugs to connect USB power supplies with their respective cables to energies the 2 WeMos + the enclosure, but that will be simple.

The CT Clamp on the mains wouldn’t work unless I add a permanent dummy load or resistor so that some current flows.

Thanks for your help!