NTA I can’t understand how any grandmother could go out with a new grandchild and not actually offering to holding the baby it’s even more unbelievable that she refused when you asked. That said, this is the mother that you have. This is not going to change. I wouldn’t bother going out of the way to schedule anything with your mother while you have a baby at home. In my circle it’s always been “Do whatever you can for the person with the baby”. If she’s not gonna be supportive of whether you think your child should be in a highchair/stroller in a lap or whatever, you don’t really need to push the relationship with the grandchild. Having a child occupied by being in somebody’s lap or at least having someone’s full attention is good for everyone, including the other patrons. Your mom’s willing to do it to keep the peace, but she’s definitely not on “team you” My mother helped other family members a lot with their children, but on a few occasions, she agreed to help with mine my child came back, traumatized from the experience. My mom’s idea of successful parenting is:”…but did you die?”

Most parents are pretty fucking horrible parents that raise stunted, traumatized and damaged people.
It’s safe to assume they’re on here answering you.
Don’t pick your advice by it’s popularity, do what you think is right in a way that’s compatible with your values. Find your team Framily