Depay, 28, reportedly wants to leave Barca in as he has fallen down the pecking order at Camp Nou.
The Dutch forward's contract expires next summer, but he wants to depart the Blaugrana in the upcoming winter transfer window.
A return to Manchester United is a possibility, with Erik ten Hag in need of a new central striker following the mutual termination of Cristiano Ronaldo's contract.
Van Gaal has praised Depay, with the Barcelona frontman part of his Netherlands squad at the 2022 FIFA World Cup.
Depay has been dealing with a thigh problem, making just three appearances across competitions for Barca, scoring one goal.
The forward came on in the Netherlands' 2-0 win over Senegal in their FIFA World Cup opener in the second half.
Van Gaal said he will make exceptions for the player as he believes he is vital to the side's chances of success at the tournament.
The former Manchester United boss said ahead of Oranje's clash with Ecuador on Friday, 25 November (via Barca Blaugranas):
“He has played 30 minutes and the next step would be 45 minutes. The injury he has makes it so difficult to decide when he can start so we have to look at him."
“But he is an extraordinary player and so I have to set aside my principles because I consider him to be incredibly important to my team. I explained this to the players, that I am doing all this for Memphis, and the players accepted this.”
Depay is just eight goals shy of former Red Devils striker Robin van Persie's record of 50 goals as the Netherlands' all-time top goalscorer.
The Barca striker made 53 appearances during his time at Old Trafford, scoring seven goals and providing six assists.
Manchester United are keeping tabs on Tottenham Hotspur's Harry Kane
According to Fichajes, Manchester United are interested in signing Tottenham striker Kane as Ronaldo's replacement.
The England captain has been one of the Premier League's top centre-forwards over the years.
He has found the net 13 times and contributed three assists in 22 appearances across competitions this season.
Kane was linked with a departure from Spurs in 2021 when Manchester City were eager to lure him to the Etihad Stadium.
Tottenham refused to sell their striker, who sits second in their all-time leading goalscorers list on 261 goals.
However, his contract with Antonio Conte's side expires in 2024, and if a new deal is not agreed, that may open the door for a potential move to Old Trafford.