Wait, can you expand on that?
Alright, but I dont have my sources with me so you can decide if you want to take my word for it or not:
Maria Leopoldina was the one who signed the independence as the Empress-Regent while urging her husband to take a side.
She disagreed with him quite a bit on how the new country should be ruled as well, being a austrian princess and all who disliked. liberalism, but she did agree with him that slavery was horrifying(being from a christian from a european court who never saw a sugar plantation before likely helped).
She and Bonifácio(who in contrast was veeeery liberal so they both balanced each other well) were the ones doing the transition between United Kingdom to Empire while Pedro was suppressing the rebellions of the few portuguese aristocrats who resisted the idea, they even design the flag and country symbols that we still have today.
Then once he was back he proceeded to kick Bonifácio out, open & close the assembly a couple times while he tried to write his own constitution, humiliate & worsen his wife's health by bringing his mistress Domitilia to the court angering the brazilian population who saw Bonifácio(who was the one who convinced Pedro to stay in the first place) and the Empress as their heroes, fight Argentina over Uruguay and finally go on a war with Portugal after Miguel overthrew his daughter resulting in him ending up returning to Portugal anyway with his new wife after Leopoldina died leaving his son who just came out of his diapers and lost a father & TWO mothers to rule the country.
Pew that was a lot wasnt it?
For things to not go
that terrible all that was required was for Maria to not blindly love Pedro and not take all of this silently.
If she actively supported the guy who stood by her side during the whole independence thingy and called Pedro out for the mistress bs & his desire to rule Portugal rather than Brazil it's not impossible to imagine the people siding with her and the rash Emperor deciding to go be King of Portugal instead of staying on a country where nobody liked him so long as it stays under his family anyway like what happened IOTL.
If she doesnt die at 29 years old thanks to, between many other factors -a better mental condition, you'd have the Empress ruling Brazil up till Pedro II feels ready to take the throne, setting the example for princess Isabel later on if she's not butterflied away.
And like I said, depending on how early Pedro I dedided to nope the hell out of Brazil, the cisplatine war could have went differently, exactly the same or not happened at all, and in case Brazil did get Uruguay(likely later when it got a better army) it would have the control of the La Plata river...and that's a different POD on it's own, sorry.
But regardless of things went on the war, the thing that held Brazil back more than anything else was undoubtly slavery and most people seem to agree that had Pedro I done enough of a good job to stay in the country he could eventually have abolished it by the end of his reign, so again with another assumption - if Maria who hated slavery with passion got it abolished by the end of her reign/start of her son's reign Brazil would have stood a much better chance of modernizing during the 19th century rather than delaying it all the way to the Vargas's dictatorship in the 1930s.