Reporting back, using qwen3.5-9b locally, this has been a pretty useful experience. I've used it for all these little questions you want to ask an LLM rather than googling them, but don't want to have a record of them online. E.g., medical questions, etc.

There is a sense of relief that starting last week, ChatGPT does not know as much as it used to about me. Now I need to convince/train my wife, who routinely uses it for personal advice. And I need to get to a larger model/better hardware so I can also start switching away from the proprietary models for my work-related stuff. Also, deleting old records, but that's just to make me feel good. They probably already recorded it in several locations.

Small steps.