Nausea wasn’t something we had to worry about until recently. We used peppermint essential oil in a roll on for quick use. We use homeopathics too - there is a jet lag pack that works well. Also, a hand fan! Great video!
For kiddos with motion sickness, you can also ask their pediatrician to give you one of those flat bags they use at the hospital. When my daughter was sick I collected two or three on the way back home and now they’re part of my kits.