Tablets are fine. You can still break them and use half of it in the prewash dispenser.

Pods are a different story.

Tables are much more expensive, and their quality varies afaik. And out of the 5 different dishwashers I've used, none had a pre-wash dispenser, only one single dispenser. But it doesn't really matter, powder cleans up everything perfectly, on any program and without additional powder in the main area of the machince. The only time when dishes were dirty after the wash was when the impeller had some gunk mechanically blocking the holes for the water. So, I see no reason to buy overpriced detergents.