You'd be amazed at the number of unencrypted analog signals still in use. They may be boring AF, but it requires some skill to know if it is boring or not. There's a lot of existing stuff out there that hasn't been / won't be updated because it's paid for and it still works.

My one bit of advice is do it all passive. If you try to start talking back, you could find yourself in a heap of trouble regardless of how benign your intentions.