How do I make a whole wall into a dresser?

You can buy shelving like this and use baskets or bins. Just make sure to attach to the wall. I used L brackets.

I love the idea of a whole wall below the window being a huge built-in dresser. I've seen that in older homes where it was truly built in, by the woodworker. That design would be a bit complicated for a novice, and I would recommend hiring a carpenter for it. However, with what they have available on the market now for cabinetry and DIY shelving, I think you could fake a built in look pretty easily. I'd start by checking out cabinets LIKE THESE. By combining different sized ones and then installing a countertop of your choice, (I'd do wood and paint or stain it to coordinate in your room) you should be able to fit them in and have a semi-built-in unit.

You can purchase closet units with drawers. Home Depot sells Closet Maid. It does get pricey but if you think of it as a great storage investment that will serve you well and last for years maybe that will take the bite out of the price. Here is an example.

If your mismatched dressers are all the same size, you can just cut the tops flush, add a plywood top spanning all three, add some decorative moulding where each one meets, then across the bottom to make them look like one. Paint your favorite color, and you'll have a wonderfully unique piece of furniture.😊