The first Ant Man had this rule where any objects that are shrunk will stay as the weight they originally were. Yet Hank Pym carries around a shrunken tank on a keychain! Scandalous!
Wrll there is also a scene in one of the movies where a plastic thomas the tank engine toy gets huge and crushes a police car. The toy that should jot weigh more than 200g crushes a car ....
I think one of the theories is that Hank doesn't actually know how Pym particles work and it's basically magic. Because if you watch it keeping weight in mind none of it makes sense.
Did they explain why in endgame a pym particles vial is only used once per person? While in other ant-man movies a vial of pym particles can be used multiple times.
Remember when Scott was about to test the time machine? They have 2 vials to use. He accidentally shrunk himself and he said they only have 1 left for the test. The 2 vials are full before they used it. He used a full vial of pym particles just to shrink down.
Because they have to shrink down to the quantum realm and come back. It uses more. It's also never made clear how many particles are in the vials or if they're full or how many a normal shrinking takes. But it is established multiple times that they have a limited supply and only enough to the job. Also, it's a comic book movie.