AirTags broadcast an encrypted ID. Phones build lists of ID’s they’ve seen and send the list to Apple.
There is no routing, no ability to send arbitrary data, no active communication of any sort. It’s not a mesh network.
The link you posted makes that pretty clear.
it means you can’t block the tracking by doing anything yourself - you’d also need to block everyone else’s devices too.
And of course you can block the tracking yourself, even though nobody is actually tracking because Apple can’t tell who owns what ID. Just turn off find my on your device.
This is a really bad thing for those of us who until now have just not connected our 'smart' shit to the internet.
Where I live in the EU they don't do sidewalk otherwise I'd have to look at ways to fight it (disassociate connections or DDoS the devices providing sidewalk routing)