I have an appradio 3. I used to have it working with aru and a Samsung s4. It did take a special cable and messing with the firmware to get it charging however.

I "upgraded" to an LG g5 which is great but is USB c and I don't want to root it. I've tried alsorts of options but it's a pain with the appradio. My latest plan is to buy a ( maybe faulty, or cracked screen) phone off eBay cheap and leave that permanently connected via a cable.. just connecting my g5 via Bluetooth for calls.

First of all can I have 2 connected at once via Bluetooth, one for aru mode and one for calls?

If so... Anyone recommend a a phone that is as powerful as an s3 or s4, will easily root and charge and just uses a regular microusb cable for mhl?

Cheers

Or an android stick? Any recommendations?

I upgraded my S4 to a S6 Edge and Samsung took the MHL feature out of the phone so I had to buy a samsung allshare cast hub and connect to it using wifi direct. Maybe this is an option for you. I'm not sure if you can do that with your LG phone. I can keep my phone in my cup holder charging while it's connected to the app radio.