I built this by testing a workflow for a service I started (hobby project) called quickish (https://quickish.site). You can just remix this (basically forks it and hosts it on your own space on quickish) for free. Can be public too. Can use the "Remix" button on the bottom right (just need a google account to login) or on CLI run: `npm i -g quickish && quickish remix create quickish/hn-flipboard`, there is also a quickish/flipboard that the HN one was remixed from (just a git fork behind the scenes).

You can work on it locally however you like, there is also a `quickish dev` command you can run in the site folder that starts up a local dev server with live reload. When you're happy with the changes just run `quickish . /flipboard` and it will publish it.

With all of that said, I am working on a version that is exactly what you are asking for. An editable board that lets you change the grid size, give it a unique url and password protect on top of a POST endpoint that let's you change the content via API (also all hosted on quickish) for that exact use case. I have a few more optimizations I am going through and will get that out.

I appreciate the kind words!