With many thanks to Soundwave's Oblivion, we have an English translation of the feature article from the 2019 Generations book that talks in detail about the new MP-44 Convoy as well as showing a lot of photos and some of the design-stage art for this, the most expensive Masterpiece ever. (as of this writing)
We're pretty sure no new secrets were revealed within these pages, but there are some insights to things like the transformation process, inspiration for some of the configurations of the accessory elements in the trailer, and that, yes, you can stack Autobot Cars in there too. One possibly new reveal in this is the relatively minor note that an iron panel has been fitted in the trailer so small figures with magnets in their feet can stand securely. Diaclone Reboot Dianauts immediately spring to mind, but it turns out the new Spike, Carly, and Sparkplug mini-figures also all have magnets in their feet.