Gifts aren't checked at the door. You are expected to bring a gift (a lot of people just bring cards, some containing cash or gift cards) but it's not required.

Parents not being able to afford to throw a good birthday party for their kid is not uncommon, either, even before all this shit went down in the world. Growing up, I was often given the choice between not having a party, or having a postponed party, or a combined party with one of my siblings or cousins.

Now that I'm married to a baker, we offer to bring the cake. That saves the parents some money. Some grandparents are prejudiced against homemade cakes for some reason, and prefer the nasty ass fake frosting of store-bought cakes, so they will offer to buy a sheet cake or a couple dozen cupcakes and sometimes the parents go that way instead. So, there are ways to save money. Of course, if you know a baker, you should not expect them to bake your child a birthday cake (and decorate it!) for free, but if you have a skill they don't have, you can work out a trade. They make your child a cake, you do work on their car, around their house, whatever. It's less of a formal transaction and more of "we all help each other." And when there's a birthday, my wife's way of helping is, she bakes a cake. Me, I do tech stuff. I can fix or upgrade computers, I can make a computer block ads and install other helpful software, I can solve a bunch of problems that are minor and small to techs, but your "average Joe" (or Jane) knows nothing about.