If you want to guard against something like this some things to consider:
Firstly, the primary conditions that allowed for this to occur was wholesale ordering of devices and a leaky supply chain. If your affinity group all decides to use the same radio, or the same type of burner or something, go out and get them one at a time at regular stores. Don't try to order them in bulk; that is a very noticeable thing to do if the state is watching.
Secondly, when possible, learn how devices work and take things apart. When the social center gets a new printer, take the thing apart, learn how it works, and check for bugs. It may sound absurd, but a social center in France found a listening device in a printer once. Check out the laptop you just bought, and only buy laptops that can be disassembled and modified. Learn how to monitor network traffic to make sure the new thing you just bought is not pinging your location back to anyone. Just the knowledge that this is being done in the anarchist community raises the cost and complexity of trying something like this dramatically.
Finally, I think that this is one more example of why building parallel communications networks, using our own devices, is something we should really be putting time and effort into. The use of LoRa communications, which utilize radio to send text based messaging over long distances, can be paired with encryption and mesh netting to form cheap networks using easy to build devices. Ham radio is another option, of a protocol that is accessible, easy to learn, and easy to obtain devices that you can either take apart or build yourself.