There really is no such thing as a dedicated burner. you don't even need NSA level threat vectors for most phone sim purchases in western countries to exfiltrate tons of user data.
I think the best way to get a burner account is to use the free services to receive text messages online. These are enough to create an account, and you can then set a pin to prevent any takeover, assuming you synchronize your account every week.
Wifi is even worse, not better..