Unless I find a reason to need my phone in my line of sight,I will probably just keep my phone on the charging mat, which is good enough for media controls if I need to do something beyond the now playing screen. Media (podcasts from Overcast) are my main reason to use my phone. I'll get used to using Rivian Nav (Google) instead of Apple Maps, but worst case having directions on the arm rest works in a pinch.
That said, there appears to be a gap between the center screen and the dash, I wonder if something like this could stick on there? https://a.co/d/07asf7t5
I'm not seeing an obvious mounting position and wouldn't want to stick mount attachments onto the wood trim but suspect I'll want a higher phone position for off-road mapping/guidance applications like onX Offroad or similar, where it seems unlikely this will become a Rivian native application anytime soon/at all. It would probably also be a better location for selecting from my own media for playback via Bluetooth to avoid taking eyes off the road.