There needs to be the ability to establish a direct wireless connection from the Roku to other devices (iPhones and iPads) in order to stream content from those devices when no wifi is available. This is very desirable for travelers who do not want to connect to dubious wifi networks
Isn't that what using hotspot from a phone is for?
Not exactly. The idea is to not be connected to the internet. Imagine camping in the mountains with no cell service. You have a movie downloaded to your laptop and you want to watch it on the tv in your RV. You need to be able to establish what’s called a Peer-to-Peer connection. Apple TV has this capability……
https://appletoolbox.com/connect-appletv-without-wifi-how-to/
Not sure if screen mirroring requires a network connection or if it is peer-to-peer. Otherwise, I would think this is way to niche of a feature, especially if it's something only Apple phones/tablets/computers can do.