Help Set Up iphone se3

Hi I hope you can help! This is an issue w. my stepfathers' phone. He is 85 & has a degenerative disease that affects his mobility. A few months ago he agreed to try an iphone. (my mom is OS & she wanted him too) He was Windows/Android based previously. He went to a local tmobile to switch services & take advantage of a Free Phone offer. He did not realize that a tmobile iphone is a different experience that going through Apple. I am sorry to report that they sold him a 2nd Gen SE over Full Price even tho the newer se3 was already released  for like $30 more. He had difficulty w. the service & set up & sought help several times from this local tmobile. They would not let him return it or leave tmobile the phone until he paid it. He did pay it & now it does not work at all he tells me. I really feel like they took advantage of him. He needs guidence what to do with this $500 phone that does not work & is worth $100 now even tho unused.

Meanwhile he went back to consumer cellular I think and purchased another iphone SE3. On this phone it says he needs to validate his identity to fully use the phone. But to get a verification code he needs to be able to add the gmail account to his phone which he cant do until he verifies his identity so it is a circular issue. He needs help setting up this new phone.

I reallly want him to deal w. Apple directly. He wants me to accompany him into the store tomorrow so I would want to make an appointment?  I walked by the store today in Philadelphia & I cant really see that being very accessible to him. There is a ton of traffic & no parking & the store is pretty crowded. He is pretty unstable (tho clearly determined!). Are there any alternative solutions? Are these issues Apple could help him over the phone? Is there another Apple or way to help him so he has a fully functioning iphone?

I hope you can help even tho he went thru these other retailers?

Please let me know. Thank you!!