Well, you could also just ask one of your neighbors whether you can temporarily use their wifi and ask for the password and describe your situation to them. Would be the easier way because I assume that you anonymize your traffic , no matter which network you use. Otherwise you can expect that...

thanks for sharing

But what do you mean in general with the term "let me see what people are doing on a certain wifi"? If you are satisfied with just knowing what people are doing on a certain wifi, it should be enough to sniff the traffic (for example with wireshark, available for almost every OS).