So I signed up for MY USPS a month or two ago. It took about 2 weeks after signing up for any package (clear or dark net) to show up on there, but after that few week period, I started getting tracking for both types of packages. Not all, but most.
As far as darknet goes I've ordered:
43 packs from 8 vendors.
39 of those were Priority
4 were Express.
Tracking showed up for the most part, on every package at one point or another before delivery. Generally (Maybe 80% of the time) showing up the day it was sent out, but 1 in 5 wouldn't show up until the day it was delivered (or at least sorted at my local PO).
The ones that didn't show up were 2 of the express orders and 3 of the priority orders. Though the few that didn't show up weren't from one specific vendor, in fact, out of the 8 vendors I used, every single one of them had packs show up on MY USPS, it wasn't until the 3rd or 4th order with said vendor that you'd get one not show up before going back to the norm and showing up again on future orders.
Hope this helps anyone curious about how well this feature works and possibly wanting to sign up for it. It really is a helpful tool, and helps put your mind at ease knowing something is being delivered that day (or delayed), especially during the holidays where postman error could be a factor.
TL;DR - MY USPS provided tracking numbers for 38 out of 43 orders on DNM purchases.
jesus christ that's a lot of packs landing.