I’m using a Reliance Electric device for my generator cut-over so I can balance both sides of the 240v as much as possible during a power outage. I’m using a manual system with a bypass lock 240v breaker in my panel. It’s rated for 30w continuous.
I also use a Powerback! alert by Reliance that runs off a battery to trigger a built-in alarm when the main power comes back on so I can switch back to regular power. I think it was around $20.
Admittedly this is beyond the scope of Sense (my apologies), but I’m not too concerned during a power outage how much I’m drawing other to not overload my gasoline powered generator and something to alert me when the power does come back on.
Aside from that, you can temporarily read using a VOM style handheld amperage meter which can go on a 120v supply line, one at a time. I don’t recommend this unless you’re an electrician or know what you are doing.
To put me back on topic and perhaps more to your point, my electric company digital power meter (includes an ethernet bridge and cooresponding app) and Sense I find is very much in sync which tells me the Sense unit is calibrated very well. Sense also gives me much more detaled information. Within 2 weeks it has found my fridge, 2 x dehumidifiers, my main AC unit, a heat pump, and the main microwave. I am missing some motors on the AC and dehumidifiers which I hope it will find later.