This has nothing to do with PayPal stealth.
Your phone carrier can see your location, PayPal definitely cannot.
You're receiving a text/call to a burner phone. The physical phone has no connection to the PayPal account and is never used.
If you're concern is privacy from your phone carrier, I suppose you could pop to an internet cafe / supermarket with wifi / etc etc. But it really isn't a concern I'd ever even thought about. It's a PAYG sim paid for in cash that is only ever used for verification codes on a ghost PayPal. It leads nowhere.
As for phones being linked by the IMEI, again, this is only apparent to your phone carrier. If you're that bothered, just buy a $10 burner phone for each account .Once again though; this is not something I think is even remotely of relevance or concern. I use 3 or 4 phones for over 30 accs at any one time.