Argentina is the favorite IMO to take one of the spots.
Martina Dominici took Argentina’s sole spot at Worlds in 31st place in TQ and was also the 3rd reserve.
However, teammate Abigail Magrstrati was 36th, just .4 off from her teammate. She also has a solid DTY which certainly helps.
I don’t know that Mexico has anyone.
IIRC Anapaula Gutierrez was 58th at Worlds and twin Jimena was the team alternate. However, they are both headed to Stanford to compete for them and I had heard they were no longer doing elite. Frida Esparza is competing at UCLA. Do they have any new seniors eligible?
Canada is also interesting because their top AAers are not eligible. Although Ava Stewart seems to be a potential AA threat for them as well. Rose Woo is another option.
So I would go Brazil with the heavy favored and then Argentina with next best chance. Canada is wild card, and Mexico unlikely.