Firefox works fine as a native viewer of the saved webp images on Linux, if you associate the file extension/file type with it. Also Chromium/Chrome can be used for the same purpose.
The only disadvantage is that the browsers are slower and they have much more inconvenient user interfaces than the dedicated image viewers, for functions like zoom and pan or passing to the next or previous image in a directory.
An alternative is to use the movie player "mpv" as the native webp viewer. This is much faster and it has the advantage of easy navigation in a directory with webp images and of easy zoom and pan (you may need to edit the mpv configuration and bind the ZOOMIN and ZOOMOUT commands to whatever keys you prefer).
The only disadvantage is that the browsers are slower and they have much more inconvenient user interfaces than the dedicated image viewers, for functions like zoom and pan or passing to the next or previous image in a directory.
An alternative is to use the movie player "mpv" as the native webp viewer. This is much faster and it has the advantage of easy navigation in a directory with webp images and of easy zoom and pan (you may need to edit the mpv configuration and bind the ZOOMIN and ZOOMOUT commands to whatever keys you prefer).