I also put laundry pods in the little compartment even though they say to just toss them into the thing where the clothes go. I do this because
The pre-rinse cycle will just flush out all the detergent before the actual cleaning cycle
The plastic shit that dissolves to release the detergent was getting all over my clothes and fucking shit up doing it the way the package instructs you.
One of my former room mates had the same problem with the washing machine. They were two compartments and you put the main detergent in the smaller one. In practice it didn't make much of a difference, but still.
Assuming the other one is for fabric softener, the clothes got agitated with plain water, then soap added during the final rinse. But if you ask my 90 year old uncle, laundry soap is a capitalist scam anyway (their pillow cases feel like they are made of old fashioned oil cloth).
The dishwasher we had when I grew up had a broken soap compartment, it wouldn't stay closed so we would just put the soap in it and shut the door, the soap would spill all over the insides, but everything was clean when it was done.