Not quite, there's a long history of legislation about consumer boycotts of Israeli products.

38 out of 50 states have laws on their books prohibiting Israeli product boycott and some form or another.

In the most egregious cases, these do things like fire School teachers if they are choosing to avoid Israeli products in their personal life.

https://en.m.wikipedia.org/wiki/Anti-BDS_laws

Read the constitutional challenges for some examples...

As far as I'm aware, the anti-BDS laws only pertain to performance under governmental contracts or similar, or are merely statements of position without legal effect.

Is there a law that prohibits individuals who are not operating under such a contract from boycotting?

All anti-BDS that I am aware of operate through government employment and contracting.

I would however clarify your statement in that the scope often extends not just to the work under contract, but personal and professional behavior outside the scope of contract.

Yes, but it's still under the authority of the contract. That means that expressing support of a boycott is not illegal, it's just grounds for termination of that employment.

That is correct.

They'll probably try to get one in now, mark my words.

...yet.

Fairly certain Tesla is not based in Israel.