Through-pocket Trousers

(Disclaimer: suggested by my daughter.)

So jumpers, sweatshirts, pullovers and hoodies are thick layer upper-body clothing; favoured casual wear for those who prioritise comfort over presentability. These sometimes have a big pocket at the front. I'd have called it a muff pocket, but given the modern implication, they're apparently now known as kangaroo pockets.

Cardigans and other clothing which opens at the front can't have such a pocket, being restricted to (usually very much smaller) pockets at the sides, if they have any at all.
Trousers usually open at the front, and are similarly pocket-restricted.

Tracksuit bottoms, or sweatpants, are comfortable trousers, often made of a similar thick, soft material to jumpers, and also ideal for slobbing about in - to the point that this is probably their primary use-case.

The case is, I think, clear for tracksuit bottoms with a large frontal pouch accessible from either side.