hi all, a little new to Android Head Units

so im currently considering to change the stock old school sound/radio system to an AHU.

however, im a little confused on the following concerns:

1. i've seen many selling 2gb ram + 16gb storage (most common).
- however, once it comes to 4gb, the price is suddenly x2-x3
- example, 2gb + 16gb costs RM400, but a 4gb + 16gb costs RM1200-RM1300
- somehow feel its not worth to pay for just additional 2gb

2. if i want to use android Auto, does the player pull its performance from the phone instead? so the 2gb doesnt matter anymore?

3. how about sound quality (if connected to Android Auto)
- does it get the sound from my phone system? like dolby, equalizer, etc
my main objective is to connect my phone and use it with Android Auto,
so my concern will be understanding if getting a 2gb will affect performance? or as long as you're connected to Android Auto, the AHU will just function as a screen and all the performance will be from the phone instead?

so if navigate using waze or gmaps, using Android Auto will be better on a 2gb AHU?