While such fares may exist, I'm pretty confident any fares found on Google Flights will simply be public fares based on country of origin as they don't do any residency verification. I'd doubt that a US airline like United would have any such fares which actually require residency verification. Just because fares are asymmetric by country of origin does not mean there is an actual residency requirement. Purchasing fares with foreign origins is frequently used by US residents to save money due to the asymmetry in fare filings.