Running a node on a phone sounds like a horrible idea. Why would this be desirable?
This is a solved problem and I never understand why people keep going back to it. Host a node or use a public node. Use a local wallet to do signing and depend on the public node for RPC calls. The vast majority of users and clients do not need to be dealing with Ethereum nodes on their own devices, they just need good key management systems.
It's desirable for a couple reasons. Firstly, the node enables whisper, which is a p2p messaging protocol. You can't do p2p messaging with a public node, and nearly zero users will host their own nodes.
Also, public nodes can be DOSed or otherwise taken down. They can invisibly filter the requests they receive. Some jurisdictions could have the nodes completely blocked.
The point here is to build a fully p2p system, so running an on-device node is an attempt to do that. That doesn't mean that public nodes can't also still exist.
Care to elaborate on how they intend to accomplish this?
This seems to have predictable limitations, and the last people I talked to a month ago said it killed their batteries. Surpriseeeeeeeee or not really?
That's part of the motivation for developing a new Ethereum client, in Nim. The theory is that the executables produced can be more readily tuned according to various device profiles, e.g. desktop clients, mobile clients, beefy server clients, and so on.
This is a solved problem and I never understand why people keep going back to it. Host a node or use a public node. Use a local wallet to do signing and depend on the public node for RPC calls. The vast majority of users and clients do not need to be dealing with Ethereum nodes on their own devices, they just need good key management systems.