You are the product and almost every organization you interact with is trying to get a piece of the action. Some of the worst offenders selling you out are your state and local governments.
that's like not having a bank account/credit card in the modern day. Doable, but extremely inconvenient and difficult to remain so.
Are you based in the EU? If so then you can do exactly that under GDPR.
Even if you do not live in California your request will likely be honored but of course I have no specifics about Fitbit.
"The Guidelines note that the processing of personal data of EU citizens that takes place outside the EU will not trigger the GDPR so long as the processing is not a specific offer directed at individuals in the EU or to monitor their behavior in the EU."
So it may be safe for google...but given it would apply to a user profile in general, including EU, maybe not?
The location of the data does not matter.
The origin of the data does not matter.
Citizenship does not matter.
These are the reasons many US firms tried to call GDPR overreaching. However if it didn't apply in this way there would be too much wiggle room to be effective.
I bet there is no option to download my data and nuke what they have before this happens either.