What are the steps to purchase a Matrics and guidance?

I have applied to the DJI Dev / SDK portal but have no heard back

Me neither..

Have you tried to email dev@dji.com?
Normally the process takes several days or a little bit longer for L2 developer.

You can order from the store at DJI.com.  There are also several dealers that are offering preorders.

Amazon can fulfil order. Check with The seller first to make sure they have one in stock. I ran into this problem just two weeks ago. Sunshine electronics are selling them and they do not have them in stock. FumFire is where I received mine from.