All of those things you mentioned are true. There is a shortage of parts and most come from China. Ready to ship models are few now and running out. Custom builds take much longer than ready to ship models. It might take months with all the problems in the world now. It could even wind up being cancelled if the parts are no longer available. July 2nd is the best they can do. Ask around and you'll see all manufacturers having problems now. I'm a user like you, not Dell. This is a user to user forum with lots of complaints like yours.   
I ordered the R11 on May 23rd, They said my order would get to me on July 2, 2020. I chatted with them and their explanation was its "custom built" which (in my opinion) is an unacceptable answer. Many way smaller companies(origin,xidax,digitalstorm, ibuypower) can get me a complete custom desktop with a custom water cooling loop in two weeks tops.  I would've accepted if they told me there was a shortage in parts or they ship it via ship from another country.
Aurora R11, shipping delay