For about $20-40 you can get a software-defined radio receiver, and use it to scan a band of interest. Since I just ordered a Hubitat and am considering my Zigbee/Zwave/etc options I thought I would scan the relevant frequencies to see if anything was going to step on me.
From what I read, US Zwave uses 908.40, 908.42 and 916MHz. So, I made a plot of emissions between 900-920MHz.
If I found the right Lutron Caseta information, it uses 431 - 437 MHz.
It's not easy to say what the few peaks in the plots may be, but there appears to be nothing stepping on Zwave's 3 freqs, and plenty of open space for Caseta. (I think the strong 915 MHz peak is related to my Insteon gear. I have a couple of RF repeaters.)
This is just a moment in time but the scanner software does have a crude live mode. Not bad for a cheap dongle and free software! If you're suspicious about RF interference on your network, this might be worth a look.
(Unfortunately 2.4 GHz is outside the range of this cheap gadget, it tops out at 1.7 GHz. But, at least we have wifi band scanner apps on our mobile devices and computers to handle that range.)