This can already be done with credit cards in Brazil.

Nubank [https://nubank.com.br/en/] lets you create as many virtual credit cards as you want, and you can delete them right away after using them. I now create one for each online transaction.

I imagine phone numbers will eventually be treated the same, specially once eSIM gets more and more common and the number is not tied to a piece of plastic anymore.

In Canada, as I assume is the same as US, even a new phone number will get bombarded with spam calls as soon as you turn it on.

I really like the idea of the post and would love to have phone numbers work like Nubank's credit card, and I would be able to create a new number (already tied to my information), use it on less reliable things, then delete it once it was over.