Where did Donnie get the money from at the end of Den of Thieves? He was handcuffed but got free. Did he find the second garbage truck? Did he divert the other thieves?
Yes. he did use the second garbage truck
Nick later goes to Donnie's bar and sees pictures of him with some of the crew members from the heist, also noticing that employees of the Reserve are regulars since it's nearby. It's revealed that Donnie actually masterminded the heist to keep all of the stolen cash for himself in a second garbage truck. After the passage of some time, Donnie is working in a London bar where several Reserve employees and heist crew members (including the garbage truck driver, one of the Reserve employees who ordered from the Chinese restaurant, and the communications expert from Merriman's crew) are seemingly enjoying their retirement and where Donnie is planning a new heist of a nearby diamond exchange.
Donnie orchestrated the whole thing..."I'm in complete control of my environment. People don't even know" he says early in the movie
He pulled the ol' switcharoo with the garbage trucks.
At 35:30 before the end (on Netflix) you see the garbage trucks pass each other, and the drivers acknowledge each other.
At 9:01 before the end, you see a photo of Donnie's soccer team. The team includes both garbage truck drivers,as well as Mack, the comms guy on the thief crew
Personally, I think Donnie should have thrown himself down the chute after the cash, for an easier escape