According to another answer about the ending of Game of Thrones, Bronn gets Highgarden:
Kingdom of the Reach - Unknown Ruler: Bronn; Highgarden is part of the six kingdoms; Bronn was given highgarden as payment of the Lannister debts.
This was of course part of the deal the Lannister boys made with Bronn so he wouldn't kill them. The remaining Lannister does not seem to have the power to give away other kingdoms.
It seems very likely that King Bran has agreed with Bronn getting Highgarden? Is this somehow explained in the series?
In particular, Bronn seems a bad choice because he does whatever monetary incentives are in play. If anyone, Bran would know that Bronn just does what whomever pays the most tells him to do
This is not a duplicate of Did Tyrion even have the authority to do this?, which asks about Tyrion's power. I am asking about why the King agreed to this, or if that's not clear from the series.