Yes, you read me right.
Apparently the system that The Directorate set up to auto-generate AppShelf files for MH3 also works for the nanoBundle, and also retroactively for the MH2 and MH1 bundles too (I think).
It's very simple - paste this URL into your browser (but don't let your browser actually go to that URL): http://www.macheist.com/order/appshelf
At the end of that URL, post your bundle receipt ID. (For the nanoBundle, your bundle receipt ID would be at the end of the URL for your bundle receipt, e.g. http://www.macheist.com/order/nano/YOURBUNDLEIDHERE )
So at the end, the URL in your browser should look like this:
http://www.macheist.com/order/appshelf/ … DLEIDHERE/
(It's important that you have that "/" at the end of that URL.)
Then press return.
Your browser should automatically download an AppShelf file with your nanoBundle serials all filled in. Import into AppShelf and enjoy!
Many thanks go to henriwatson from the Blue team, who led us to this hot tip over MH Chat (And for catching the error I made over the ending slash in the URL).
AppShelf: MacHeist 3 Loot
AppShelf: nanoBundle 1
Check Reciept Page for nanoBundle 2 AppShelf Files.