What exactly is the benefit over Waterfox or Ungoogled Chromium here? The FAQ https://kagi.com/orion/faq.html#firefox seems to be things that are specific to Mac or have privacy features already offered by open-source alternatives.
On the other hand, it promises to be a simple yet usable (builtin adblock + privacy) browser. Ime, brave is probably the closest however it has a lot of nagging around their crypto and ads.