Bombol Pop-up Booster Seat
This is a crazy-cool pop-up booster seat for babies and kids 6 months and up. This is one of the coolest baby gadgets I've come across, and not many people seem to know about it. The seat folds flat to about the size of a laptop and sets up by just pulling the tab. It can be attached to most chairs and the case doubles as a chair-protector. It is shockingly strong–I've used it as a step-stool in a pinch. The material is wipeable and everything is easy to clean. This was amazing to have at hotels, Airbnbs, and friend's houses.
Now our kiddo is older and prefers to just sit in a chair, but it could definitely be used well into the toddler years.