Hi Umberto
I did some testing locally as I'm not familiar with how the EWWW IO plugin works, but based on my tests it appears to work correctly with a View paginated via ajax.
First, having installed the EWWWIO plugin I let it optimise all the images. In the upload folder I can see that for each img size EWWW generates a webp file with the same name as the original, appended with .webp.
So the thumbnail version of my file dogs1-150x150.jpg has a corresponding dogs1-150x150.jpg.webp file generated. Likewise all the other images and sizes.
In the EWWWIO settings, it seems that the way it works is to update the rewrite rules in .htaccess so that any request for the original .jpg image will instead return the webp version, though you wouldn't know it from the requested name. So the web page requests dogs1-150x150.jpg, and the server returns dogs1-150x150.jpg.webp.
I set up a View to query some posts, where it outputs a custom image field from each post. The View includes pagination via ajax, initially showing just one page, then paginating to the second etc.
You can see in the screenshot the network requests and what was returned.
The initial page requested dogs1-150x150.jpg, but as the screenshot shows, it is actually the webp version returned by the server.
I then paginated (via ajax) to the second page, which similarly requests cats1-150x150.jpg, but where the server actually returns the webp version (thanks to the rewrite rules in .htaccess).
If you use the browser tools to inspect the page markup, it looks like it is using the original .jpg files (because that is what is being requested), but what's actually being returned is the webp version of the image.
So, it appears to be working exactly as expected.