Actually, I want to think more about the theory of change here. It's conceivable that a ProPublica article could actually make the situation worse, e.g. by advertising the existence of the helmet to other abusive employers, or causing abusive employers to rework their labor practices in a way that looks better to the press but is actually worse.
If the company that makes the helmet is based in a country with good government, maybe a reasonable regulation would be to score workers on productivity, but place limitations on the scoring somehow. E.g. the helmet stops showing the worker's location when they've spent too much time in the heat. Or the helmet estimates the fraction of the workday that the worker spent offsite, but all workers who spend 20% or less of their time offsite are given a score of 20%, so the employer can't force the worker to spend more than 80% of their time onsite. I don't think productivity scoring has to be dystopian in principle; generally speaking it seems reasonable to pay people according to how productive they are.
You could also argue for regulating the helmet out of existence, but I assume in that case it would just be built somewhere else with lax regulations. So the trick is to put in regulation that creates a humane experience for workers, but not so much that Qatar is incentivized to contract the development of a new, more draconian helmet in a different locale. I don't think this should be too hard, because creating a humane experience for workers should also help productivity to a degree.
There's also a security dimension here -- you don't want abusive employers to be able to circumvent these limitations. So you could make it so the helmet only runs code which has been signed with the company's private key, or have a lot of the functionality server-side.