If it's fishing, you can push back. If it's reasonably targeted to result in actionable evidence, probably not :)
"Or is simply working for a company being sued sufficient to be compelled to produce my personal devices?"
Probably not quite without a good reason. To be clear, it's not just companies. If you were, for example, getting divorced, acrimoniously, expect to have your personal devices subpoenaed (my ex was a family lawyer, this happened all the time)
"This entire concept is deeply troubling to me."
Remember that the goal of the civil justice system is not to let people hide things. They just want to resolve the disputes. The best way is "put all evidence and cards on table". So they try to do that.
In cases where it is embarrassing or whatever, you can get protective orders on who may have access, etc.
But you should fully expect, in any lawsuit, company, your neighbor, whoever, that if they have good reason to believe you have relevant evidence on your personal device, you'll be forced to produce it.
If you don't have relevant evidence, i would push back hard.
But also note. Misuse is strongly actionable:
"(1) Avoiding Undue Burden or Expense; Sanctions. A party or attorney responsible for issuing and serving a subpoena must take reasonable steps to avoid imposing undue burden or expense on a person subject to the subpoena. The court for the district where compliance is required must enforce this duty and impose an appropriate sanction—which may include lost earnings and reasonable attorney's fees—on a party or attorney who fails to comply.
...
Paragraph (c)(1) gives specific application to the principle stated in Rule 26(g) and specifies liability for earnings lost by a non-party witness as a result of a misuse of the subpoena. No change in existing law is thereby effected. Abuse of a subpoena is an actionable tort, Board of Ed. v. Farmingdale Classroom Teach. Ass'n, 38 N.Y.2d 397, 380 N.Y.S.2d 635, 343 N.E.2d 278 (1975), and the duty of the attorney to the non-party is also embodied in Model Rule of Professional Conduct 4.4. The liability of the attorney is correlative to the expanded power of the attorney to issue subpoenas. The liability may include the cost of fees to collect attorneys’ fees owed as a result of a breach of this duty."
