working iPhone 7 or 8 (Seven Oaks)

I'm hoping someone out there upgraded their phone and has a working iPhone 7 or 8 that is not tied to a specific carrier (unlocked). I would love to get my mom off her trashy flip phone by setting up an iPhone for her and showing her how much easier it would be for her but I don't want to sink a ton of money into a phone in case she flatly refuses to use it (you know how older parents can be)