Okay another mom told me they would load up a little liquid in the bottom of the straw, hold the top with their finger and put the bottom of the straw in the babies mouth. They did this a few times and then they held the straw closed and this forced the baby to suck a little and the mom would let the liquid go. After a few times of that. Baby got used to sucking from a straw. Other than that it was largely messy practice.
We used these then transitioned to oxo straw, then to munchkin weighted straw cups while also using the small ezpz open cup during meals so she could work on both https://a.co/d/86vfvKo
The First Years Squeeze & Sip Toddler Straw Cups - Squeezable Transition Sippy Cup with Silicone Straw - Toddler Feeding Supplies - 7 Oz - 3 Count - Ages 6 Months and Up https://a.co/d/d2uo1Pl These are working really well for us. I just cut the straw a little bit so his mouth can touch the base of the cup.