I took a turion 64 dual core to Iraq and it worked great, the next time I came back with a core 2 duo with a 7900gs go and that was a terrible mistake. Those were a long few weeks for a reliable in hot weather computer showed up again. We played bioshock, battlefield 2 and mods for it, fallout 3...
They're spendy but I get 7-9 years out of the XS power/northstar AGMs in pickups. The oldest one right now is 6 years and a few months old and it still works fine though when it's not going to be used for weeks I put it on a tender or if it's been a fewer amount of weeks I'll put it on the 7 amp...
This is why I emplace laptops and they're just somewhat more mobile desktops in our use. They move in nice cases too. I do keep a ~$1500 laptop though for the portable stuff though.
I use Plexamp and Android auto too but most of the flac except the gigantic grateful dead discography is stored locally on the phone too. I do this to save battery and to make it work without cellular. There's plenty of places in AR and other places where cell phones don't work or infrastructure...
https://www.amazon.com/AAWireless-2022-Wireless-Automatically-Companion/dp/B0B71XC7VG these work great I have 4 of them. It enables you to use a fast usb pd charger to charge the phone instead of the measly 930 milliamps that most cars put to the port.
Shield still gets updates sometimes but sunshine and moonshine have taken over and are actively developed to replicate the game stream experience. edit not moonshine it's moonlight and i'm drunk.
I don't know what you mean by older but I bought one of the new ultra books a few months ago for storm chasing with the 1360p i5 and 32GB RAM and no dgpu and tried doom 2016, silent hunter III and IV, and battlebit remastered. It ran all of these just fine as well as Radar Omega.