I'm on D9.4.x using ddev as local server.
The site have already configured Image optimize and Image magick
There's a image optimize pipeline that is the default for all the image styles.

Now, I've been asked to convert all the sites's images into webp.
I've tried alternatively webp and imageapi_optimize_webp but I can't get to neither of those to work.
I've add to the "lossless pipeline" the "Webp" processor they provide, but the images after that are still printed in the html as jpg\png.
While using imageapi_optimize_webp the webp version of the file is actually created, alongside the jpg one, but in the html is still used the jpg one. With webp, the webp file isn't created at all.
I've tried to put the "webp" processor either as first or last of the pipeline.
I've tried to debug both modules and the code seems to work fine.
I've obviously clear (multiple times) the caches.
I've also tried with a D9 new installation and even there the module didn't work, so I'd say something wrong on my setup.
For now I've solved the issue relying on the webp converter new from D 9.2.x (#1 or #2), which seems to work even if using imagemagick instead of GD2 as toolkit
However, it's highly probable I'll be asked to implement responsive image styles on the site, and the core webp converter for now don't support older versions of Safari and Internet Explorer, so I'd like to know how use either one of those modules, thanks.