Pretty sure you can own a tank in the US as long as the main gun is disabled, and the machine guns need a proper permit or also disabled.
You could get a permit for the main gun, too, I think.
https://www.oregonlive.com/pacific-northwest-news/2015/10/2_men_killed_in_tank_explosion.html
I know a guy in New Jersey that restores AFV’s. He had a couple of investors that wanted a tank restored with a working main gun. He refused for technical reasons. He also know the guys in the above article that died when the breach exploded on their M-10 Hellcat tank destroyer. And THAT is the reason he doesn’t mess with main guns.
Houston attorney Tony Buzbee bought a WWII tank, and parked it on the street in front of his house in River Oaks (ritzy rich part of Houston).
https://www.texasmonthly.com/the-daily-post/complete-story-river-oaks-tank/