Hi there,
installing GP or GP Site will not convert Divi content – that will have to be rebuilt if you wish to remove Divi.
Those steps are correct – but i would not suggest doing this on a live site as you will need to make changes to the Site that is imported, as well as your existing content. Instead move your site to a Staging site ( most Hosts offer this service ) then perform those steps, make your corrections and the push the Staging Site to Live.