As an individual, I'm not a data controller.

Not necessarily (although, based on your analysis, your risk seems pretty low). I've written some thoughts up here: https://neilzone.co.uk/2021/11/cctv-or-ip-cameras-outside-your-home-and-the-uk-gdpr (The Fairhurst v Woodard judgment, above, was one of the triggers for this. The judge did not regard the Ring doorbell as a problem (i.e. its use was justified) in that case, but then the case did not consider the so-called "domestic purposes" exemption anyway.)