Probably the US should mandate (by edict or incentive) its own industry to build EVs rather than importing a strategic asset from a strategic competitor.
Why would you want to be in a trade war, yet alone with the whole world? The US has many friends, there's more than just China.
Also, you suggest that a trade war is bad, because you might no longer be able to buy stuff from other people. But then you suggest that the right way to prepare for a trade war is to pretend that you are already in one, ie do to yourself what the enemy would want to do to you in a trade war? (That being limiting your ability to buy from the rest of the world?)
They did. But the local political dysfunction meant they ended up making Elon Musk the richest man in the world and he's now trying to take over the government in cahoots with someone who is fighting a culture war against EVs, while only getting to 10% EV sales.
China spent similar amounts and has a vibrant, world leading EV marketplace, supplied by their vibrant, world leading battery industry, and 50% EV penetration domestically and export plans that terrify the countries that chose not to follow this path.