As far as I am aware there is not a way to do this directly with square appointments.
Other partners, such as SalesVu do have some apps for this.
However, they have changed their pricing structure and you're starting at $100/mo minimum.
I have moved to using the web forms through the weebly online store.
It allows me to get a lot more specific info from a customer before booking.
Although you have to answer each one individually and it comes as an email.
I don't see this working well for fast paced situations in a restaurant.
A quick look at the Square App Marketplace and i didn't see much for waitlists.
Just other appointment options. You might take some time and search there and read into their services a little more.
This is clearly a much needed service, which I guess is why those that provide it really charge for it.
