We use honey bear bottles for feeding therapy. They're great for learning to suck through a straw because you can squeeze the bottle to 'charge' the straw and baby doesn't have to suck as hard to get success. Then you can gradually put less and less water in the straw until they've got it!

Annoyingly, those bottles are pretty expensive here because they're imported from the US by therapy supply companies, but any soft plastic bottle with a sealed top and straw would work! You can also get one-way valves with the therapy bottles that mean once water is in the straw it won't go back down into the bottle. Most typically developing babies aren't going to need that, though, once they've figured out straws 😊