The Avengers: Endgame Minimates figure series, from the hit film and produced by Diamond Select Toys, is currently available to purchase. There's a special exclusive Marvel Minimates box set that includes four figures: Tony Stark in his Quantum suit (with alternate heads for Hawkeye and Ant-Man), Black Widow (with an alternate head for Nebula), Quantum Suit Hulk, and Quantum Suit War Machine.
There are four two-packs available exclusively at Walgreens stores, each pairing two cast members from the sure-to-be-blockbuster film: Iron Man with Thanos, Black Widow with Hawkeye, Hulk with War Machine, and Quantum Suit Captain America with Quantum Suit Rocket. (The last pack also includes alternate parts to turn Captain America into Thor, complete with Stormbreaker)
You can currently pick up these, plus plenty of other Avengers: Endgame collectibles, over at Amazon.com.