I am a Registered Investment Advisor. I own my own firm.
A retiree can make a very good part time administrative assistant to a person like myself or an insurance agent. 15-25 hrs per week and a pleasant office environment. 15-20 per hour.
You would need a spotless criminal record, good written skills, understanding of msft word/excel and be professional in manner and appearance.
Since you're on Medicare make sure you're new MAGI doesn't increase your premiums for Part B and Part D. If you have a nice income that's at the top of the limit before being charged a higher premium, it might be best to do charity work for free (i.e. I'll probably volunteer more at my church).
https://libertymedicare.com/blog/medicare-part-d-part-b-premiums-by-income/