But doesn't it imply that the only way to not be the product is to be the customer? In this case, we see that being the customer is insufficient to not be the product.

No, being a product or a customer stand in no relation to one another. You can be neither, either, or both. If you don't want to be a product, you have to work on that, not on being a better customer.

No, the only way to not be the product is to not provide PII to big tech, or their downstreams that immediately shuttle your PII to big tech.

Advertising doesn't technically need PII, any kind of II is enough (PII typically refers to things like your name or face or address).

Every app these days requires your unique and unchanging advertising identifier to log in. You can’t get an Apple ID or Google account, or order a pizza or make a dinner reservation without it.

You might know it as your phone number.