Can't you get generic batteries?
Just make the phone with a easily replaceable battery by the user.
The big push will come in November/December. I want to extend the life of the device, so I am going to replace that battery as late as I can.
I went to the Apple store & got my new battery last week. They were busy.
Tried to make an appointment with the local Apple store a few weeks ago to have my wife’s iPhone 6 battery replaced and there were no slots available so I went on Amazon and bought the Homsum battery replacement kit (<$30) and swapped it out myself. Not for the faint of heart but there are videos detailing the steps and the only pain I had was dealing with those tiny screws holding down the heat plates.
There was a 4-6 week wait at my local Apple Store, so I opted to send it in. It should take a few days....I guess we’ll see!
But are they really worth the price differential?

BLU Vivo 8 cost: $248.99 (Prime)
iPhone X cost: $1,299.00 (NOT Prime)
I am not questioning that the iPhone X is a better phone in many aspects (but not all). But is it $1,050 better?
The point is this: if you pay $814 for an iPhone 8 or $1,300 for an iPhone X, you're going to jump through hoops to keep it viable as long as possible...that is totally understandable.
If you pay $200 - $250 for a phone, if it starts messing up after a year or so, you can just go get an upgraded phone without massive pain.
I suppose if you were a professional videographer, it would be worth the money to get the improved video. I honestly don't understand, outside of narrow professional reasons, why a person would waste the extra money? Can somebody explain this to me?