How do you travel with baby and still feed them breastmilk? (If breast is not available)

C

I'm a FTM who wants to breastfeed exclusively. One thing I've been thinking about is if my baby is with dad or grandparents (say the zoo or on a walk) and the breast is not an option for feeding... what do you do?

Say I am not there or unavailable to feed for some reason, how would I still allow for my baby to drink breastmilk?

Do babies drink breastmilk cold? I've seen warming devices on amazon, do they work?

My friend bottle feeds and just mixes up a bottle for her baby but what can you do to give your baby breastmilk while on the go (without mom)?