Welcome to the Wyze User Community Forum @joaopaulo! 
Wyze has indicated that the largest supported card is 256GB, however there are users who have larger ones in service operating successfully. The unofficial word is whatever you can get to work.
The U rating on the SD Card refers to the speed at which the card can be written and read. U3 cards are 3 times faster than U1 so it will be faster loading and streaming when trying to view video.
A Class 10 card is a U1 which is equivalent to V10. U3 cards are actually V30 and do not have a Class rating like the Class 10 U1 V10 cards.
My strongest recommendation to anyone buying large format SD Cards is to buy High Endurance cards that have been specifically designed to run in continuous record cams and dash cams, have a robust warranty period\policy, and are recognized name brands.
Cut rate SD Cards that aren’t designed for continuous long term recording in moderately harsh environments tend to fail quickly. There are also issues with counterfeit cards out there being sold as name brands.