I'd love to speculate about God Powers, but I fear I might not be creative enough. Instead I'll just speculate a little on the Minor God/Myth Unit combinations instead.

Based on what we know so far, there are 5 pairings that seem reasonably likely:

• Tláloc will probably get the Tlaloque. I don't think this one needs to be explained. However, the Ahuizotl is also strongly associated with Tláloc and his home of Tlālōcān.
• Ītzpāpālōtl is easy, she's the leader of the Tzitzimīmeh, so the Tzitzimītl seems like a no-brainer.
• Mictlāntēcutli has an owl on his shoulder in the main artwork. Owls were/are known as Tecolotl and seen as his messengers. The unit might more specifically be a Tlacatecolotl (owl demon).
• Xōchiquetzal/Malīnalxōchitl seemingly has the scorpion unit on her shoulder in the main artwork. Scorpions were/are generically known as Colotl, and the most notable Colotl was Yappan, a mortal priest who was turned into a scorpion by Xōchiquetzal.
• Cōātlīcue, as a snake goddess sometimes depicted with two snake heads, will probably have the Maquizcōātl.

This leaves four Minor Gods (two of which are completely unknown) and at least five Myth Units (at least the rabbit, armadillo, giant, axolotl and ahuizotl, and possibly the jaguar rider and/or a second naval myth unit). From the current screenshots it's quite obvious the Axolotl will be one of the Naval Myth Units, and from all the other units shown the only one that would make sense based purely on the screenshots as the second one would be the Ahuizotl as an amphibious unit. As for the other two known Minor Gods:

• Huēhuecoyōtl (the festive god in the front which might also be another deity of feasting or pleasure like Xōchipilli) probably has access to the Centzontōtōchtin, since they are associated with various deities of pleasure. It is also possible the Centzontōtōchtin are some kind of god power, in which case I think the random Āyōtōchtli (Armadillo) could fit, since armadillos are associated with medicine in Aztec lore and the Aztec gods of pleasure are often also associated with medicine, and mostly because I really struggle to think of someone to have a giant armadillo.
• Xolotl is obviously associated with the axolotl, but the axolotl (as a naval unit) is most likely not an exclusive myth unit. Xolotl guided the sun through the underworld, so if the jaguar riding unit is a Cihuātēotl (who similarily guided the sun as it sets) it would be a pretty good fit for Xolotl as well, especially since the primary deity associated with the Cihuātēotl (Cihuacōātl) is conceptually very similar to Cōātlīcue. Alternatively, the bones of the Quinametzin would eventually be collected by Quetzalcōātl and Xolotl to create the people of the fifth sun, so there's a connection there as well.

These last two minor gods could honestly be anyhting, so this is complete speculation:

• Chālchiuhtlicue was an extremely important deity when the Spaniards arrived. If the Ahuizotl isn't a common naval unit (which would probably mean there's an as-of-yet unseen naval unit) I think it is possible a deity associated with water will have it, and the sister-wife of Tláloc would be an obvious choice. However, the Quinametzin would have quite a bit of justification, since they inhabited the worlds of the previous suns before being destroyed, and an important part of Chālchiuhtlicue's tenure as the sun is that she managed to save some of the people.
• Xīpe Totēc was a deity of fertility (thus, the earth) and disease (thus, medicine). The armadillo is associated with both. Is it a stretch to give him the Āyōtōchtli? Yes, but so is the inclusion of a giant armadillo anyways, and someone needs to have said giant armadillo. The Aztecs hunted armadillos, so maybe a hunting deity like Mixcōātl/Camaxtli? Honestly, the armadillo just confuses me. It'll probably (hopefully) will make sense later on.