it is a NFA Destructive Device (DD) and requires a registration and tax stamp.
The rockets are another matter. They would have to individually registered. Also you need a special explosives storage license to store them, which is very expensive and requires more expensive storage requirements. Which is not likely to be issued to you.
Truth is no one will sell you any RPG rounds in the Untied States, if they make them at all. No one wants that liability or legal consequences if you misuse them.
The launcher, as a DD is really just a pipe with sites and a triggering mechanism and trigger with a pistol grip. Thousands of nonoperative RPG launchers were sold years ago, they are basically display items.
You can own an operating launcher, but nothing to fire out of it. If you want a NFA item with some utility buy a suppressor, one of the larger ones (.30 caliber plus) so you can have threaded barrels on different guns, and make them quieter, and lower the recoil with the weight.
You’ll get years of use and enjoyment out of them if you shoot guns. Some of the better ones can turn a .22 LR gun into a sound lower than a pneumatic nail gun or heavy staple gun. A RPG launcher is just a display item, that can shoot nothing.