It is not possible to customize updown.io status pages design or logo for the moment. You can find a couple suggestions here if you want to add your vote:
https://updown.canny.io/general/p/custom-logo-for-public-status-pages
https://updown.canny.io/general/p/custom-css-for-public-status-pagess
But it is still possible to use our read-only API key to build truly custom status page or dashboard in javascript if you need something different. Our API accepts CORS requests so you can built it in standalone javascript.
Here are some example custom status page made by our users that you could start from:
https://github.com/nya1/updown-status-page
https://github.com/Hexstream/status.abc.hexstream.xyz
https://github.com/SocialGouv/dashlord
https://github.com/MTES-MCT/updownio-action