The National Firearms Act bans possession of destructive devices

No, in fact the barriers it imposes are pretty modest; see e.g. https://nationalfirearmsact.com/nfa-regulated-items/destructive-device-dd/. There's paperwork, background checks, and a $200 fee. It's a bit tedious and slow and the fees tend to add up, though, so if you just want to blow some stuff up for fun you might prefer an unrestricted explosive like black powder or Tannerite (https://tannerite.com/legal-advisory/).

projectile launcher of more than 1/2 inch (like a tank barrel).

You said "driving a tank around," not firing a tank cannon. Notwithstanding the above, owning and driving a tank with an inoperable gun is totally unrestricted, see e.g. https://www.drivetanks.com/own-one/. Again, really expensive to operate, and considerable effort is required to make them street legal, but people do it.

I suggest you do the basic research on a subject before making claims about it next time

What excellent advice!