Stemming from our thread offline, I had an idea that maybe we could provide some self-hosting option as well. I still want to help make sequoia easy to deploy for non-technical people and happy to keep submitting PRs to that end. But since I also have my own Cloudflare account, I realized: why not self-host the web worker at least? I could use my own branding (colors, mainly), etc., and make the transition less jarring, not to mention can leave the default referrer-policy.
Off hand, I don't think much would be necessary. Maybe add a GET-only route for CSS and consolidate use to make things easier to update, define some CSS variables for most of the branding people would want, etc. Or maybe even a configuration value to override that with their own CSS path.