No offence OP but the Pixel 3 is 6-7 years old and lost software support 3-4 years ago. It is ancient hardware in phone terms. It was never sold new here and probably the reason why they never installed the profile into the OS. It’s not like the old days pre VoLTE where if the operating bands lined up the phone would work. Perhaps the manufacturer doesn’t want the phone to work here and specified this SKU accordingly. It’s good that you’re trying to get it to work but I’d go back to whoever sold you the refurbished phone last year and try to get a refund.