Navigate to https://samesite-lax-demo.vercel.app/ and use the tool there to set a SameSite=Lax cookie.
Come back here and try navigating back to that site using these two methods:
This link: https://samesite-lax-demo.vercel.app/ - do you see the cookie you set?
Now fire up the browser developer tools network panel and click this button - did it send the cookie header?
Cookies on the other domain as an SVG image embedded from
https://samesite-lax-demo.vercel.app/cookies.svg:
JSON data returned by
fetch("https://samesite-lax-demo.vercel.app/cookies.json", {credentials: "include"})
That endpoint has these CORS headers:
access-control-allow-origin: https://simonw.github.io
access-control-allow-credentials: true