You could absolutely get this working with GitHub Actions with a bit of creativity.

I've been playing around with my own image-diff tool for this kind of thing, but it's not yet in a decent state: https://github.com/simonw/image-diff - there are other, better options out there such as https://github.com/mapbox/pixelmatch

Needle is an older system that did this using Selenium - updating that to work with Playwright (or Playwight via shot-scraper) would be an interesting project: https://github.com/python-needle/needle