Sidewalk is carrying all kinds of data from other users. You have absolutely no idea what. It’s a loosely defined system that Amazon controls remotely at their will. The encryption stops you from snooping like any other TLS traffic, but Amazon itself is the receiver on the other end. And it piggybacks on your own internet connection - 80Kbps is a
huge amount of data.
Find My identifiers have a single purpose, are useless to anything but the owners device, cannot be used by Apple for tracking, ads or whatever, and id be surprised if the entire payload after a day out is > 8KB total. These look completely different to me.