I have one product in classifieds with webp images format some time back, testing, no problems in sizing the image even in colorbox, OwlCarousel or with ZC.

Interesting use of <picture>, what about the browsers not HTML5!! They don't support webp or <picture> ether..

Unfortunately, looking at site logs many of my visitors are not up to HTML5 browsers yet. But then again who is using the older browsers? Even with my iPhone 11 I have no problems with webp!! If I wanted to keep supporting older browsers I'd still be using mobile detect! Which I don't.. I went a bit deeper into why the older browsers... found many newer browsers don't support the plug-ins that the script-kiddies love to use.. Looking at site logs again and doing scans, those visitors that don't upgrade, more then likely can't use what I sale anyway GEOPDF's and GEOTIFF's...

If change wasn't good, I'd still be coding in ML and the BBS would still be king....