My file manager can’t handle them but my browser can.
Edit: and good luck uploading the format to the majority of webforms that aren’t faang.
If you are using an image optimization service like Imgix / Cloudflare Image Resizing then it doesn't really matter, image can be uploaded as any supported format and will be sent to the end user according to their "Accept" header
Not even Google supports webp uploads in many of their web apps, and it's their format.