I don't know what 529 you guys invested in but Utah's 529 which anyone can use whether or not they live in Utah allows you to invest in regular old Vanguard funds like VSTSX. They also offer target dates funds that handle gradually shifting to a more conservative allocation as enrollment date nears if that's what you want.

I agree that not all 529s are good, only 2 plans received a gold rating from Morningstar in 2022: Utah & Michigan. I wouldn't choose anything other than those.