They really don't. They pair each serial number to a developer, but they aren't tracked any more than retail devices. Remote bricking is also definitely not a thing they currently can or ever have done to switch hw. Historically they've banned known leaked dev units and nothing more.
If there was anything it'd be present in retail too and presumably would've been documented, as dev firmware almost always has identical sysmodules compared to retail (aside from the addition of dmnt/dmnt.gen2, cs, tma/htc, and couple other things).
Edit: In addition, Nintendo also doesn't require dev units to connect to the internet to "activate" or anything. In fact you need to go through a number of steps to connect to the internet at all. They're just generally very lenient with switch stuff.