Go on ebay and find a newer, but not newest phone for a lot less.
I bought a new in box iphone 6s for $165.
Redpocket will give you cell service for varying rates from $8.25 a month on an annual plan to unlimited with 3gb @highest speeds for $20.00 a month or unlimited 10gb @highest speeds for $30 a month.
Pick which network, T-Mobile, Verizon or ATT, they send you a sim card and even a tech neanderthal like me can activate it.
I have used redpocket things,
I like mintsim too.
Lots of deals right now for all the MVNO plans
Moto G Play 2021. $158 on Amazon. Does 4G and LTE and everything just fine. If you want to play ginormous bandwidth sucking, processor intensive games on your phone you can afford an $800 phone.
Seems like this rollout could be done as backwardly compatible.