Using Appwrite for simple web app on a static html css page

Hello! My customer has a static html css Publii site and would like to be able to add a basic notification text box to the site with an expiration date. Management must be as simple as entering a login and password, receiving a graphical user interface with a topic, text, expiration date, and SAVE, and then logging out. Is this achievable with Appwrite? If yes, could you pls point me to relevant documentation. Also, how many workdays would you expect from novice Appwrite user to create something like this?

Also, is there any real difference to use Supabase over Appwrite? Both are Foss and seems to do the same thing.

I think yes, but obviously you need to build the fronted with Js+html+css

Appwrite is probably easier to use, permissions are probably easier to setup, it has more SDK, allows writing functions in more languages and they're probably more powerful and also Appwrite is cheaper and easier to self-host, plus you can migrate very easily from self-hosted to cloud or backwards thanks to the built-in migrations feature.
But of course Supabase has advantages: vector database, direct access to the DB, and functions are edge functions.

The choice obviously depends on your needs