If you’re in the US, unpaid overtime is only permissible if you’re salaried exempt. To be salaried exempt:

• you must make at least $684 every week ($35,568/year)
• your primary job responsibility must be one of the following:
  • executive - managing the enterprise, or managing a customarily recognized department or subdivision; you must also regularly direct your work of at least two FTEs and be able to hire / fire people (or be able to provide recommendations that are strongly considered)
  • administrative - office or non-manual work directly related to the management or general business operations, or
  • learned professional - work which is predominantly intellectual in character and which includes work requiring the consistent exercise of discretion and judgment, in the field of science or learning
  • creative professional - work requiring invention, imagination, originality or talent in a recognized field of artistic or creative endeavor
  • IT related - computer systems analyst, computer programmer, software engineer or other similarly skilled worker in the computer field
  • sales
  • HCE (you must be making at least $107k per year)
• your pay must not be reduced if your work quality is reduced or if you work fewer hours
  • for example, if you work 5 days a week, for an hour a day, you must get the same pay as if you worked 8 hours every day. There are some permissible deductions they can make - like if you miss a full day - and they can require you to use vacation time or sick time, if you have it - and of course they can fire you if you’re leaving without completing your tasks… but they still have to pay you.

Check out https://www.dol.gov/agencies/whd/fact-sheets/17a-overtime for more details on the above.

It’s quite possible you’re eligible for back-paid overtime.

Note also that the minimum exempt wages are increasing in July.

Re your “cover my expenses just to exist” bit and the follow-up about employers catching on and pushing abusive shit… if this is related to a disability make sure to look into getting that on record and seeking an accommodation. If your primary job duty is X and they’re pushing you to do Y, but your disability makes Y infeasible, then it’s a pretty reasonable accommodation to ask to not have to do Y (assuming your HCP agrees, of course).