You can do this locally though, it just takes like 200 GB. I've run an Ethereum full node + eth2 beacon chain node on my Macbook Pro for local development, took like 10 hours to sync IIRC and just worked afterwards. I still use Infura for projects though bc I don't really see the value in running my own hosted client for pet projects. If I was doing a production app I'd likely use my own w/ a 3rd party service for backup/HA.
Ethereum has plans for state expiry, so that to maintain a verified copy of the blockchain you won't be expected to maintain a growing list of state transitions since genesis anymore.
A sister initiative, weak statelessness, means that you will be able to verify the validity of the chain without needing to store state at all.
But that's just it.. One would have to stand up a server that hosted the 200gb, so their Iphone users could consume the data. Or they'd go through a central server.
