what wysiwig web editor and builder works with macOS Monterey 12.0.

The SeaMonkey browser has a "Compose" mode which is a simple WYSIWYG webpage editor. I use it for a simple work webpage. It is definitely not an editor for modern day webpages, but for simple, it works well.

I can fire it up on my M1 Max Macbook Pro under Monterey.

https://brew.sh

brew install seamonkey

You will need to tell System Preferences -> Security & Privacy -> General (tab) to "Allow" the launching of SeaMonkey after your first attempt to run it.

Then look in the SeaMonkey -> File -> New -> Compose Page

Have you tried EverWeb. Many have migrated over to it as it has a GUI similar to that of iWeb. It also lets you start with a blank theme and build your own. You can also copy and paste text and other elements from a published site into a new Everweb site in construction. There's a demo version that will let you create and view the site is Everweb's browser but not publish.

In a browser, search on these keywords: wysiwyg web creation tool and explore the results. When you find something interesting, inquire of the developer if that product is currently or planned for Monterey support.

Don't rule out searching the Mac App Store with key words web design which will reveal applications such as Sparkle.

And… https://alternativeto.net/software/sparkle/?platform=mac