Diablo Immortal is early in technical alpha, so I don’t expect emulators to work properly at this point. However, I was able to load Diablo Immortal in BlueStacks 4 with the help of a reddit user in Discord: Alek.
Reforge Stones become available at max level, and allow you to change the attribute of your gear.
Once you acquire a Reforge Stone, head to the Blacksmith and press the Reforge tab.
You will get this UI to select the attribute you wish to change, and the option to select a Stone to randomly obtain an attribute of that stone family. You can unlock up to 3 attributes per gear at Rank 11 and Rank 16. When the item has three attributes from that family, the stone family set attribute unlocks.
In Diablo Immortal technical alpha, Paragon is unlocked at level 45. It will unlock at level 60 when the game is launched. There are four types of Paragon, and so far it looks like a linear progression: