I'm searching for an available new compact pocket camera with 600mm equivalent telephoto lens, something like the Panasonic ZS80 or similar. I can't seem to find anything new on Amazon.
Camera will be used mostly for birding. Preferably with wifi and 4k video recording.
Similar to what the prior response reported, there don't seem to be many options. I think you pretty much have to have a viewfinder for this use, and that plus pocketable plus 600mm equivalent leaves you AFAIK only the Nikon A1000 in addition to the already-mentioned Panasonic ZS80 and Sony Cyber-shot DSC-HX99--plus their predecessor models.
But I have to wonder: have you seen many high-quality photos of the sort you want to capture that were taken with such cameras? At the long end, the lenses on these cameras are going to be like the equivalent of f/36 or something. Diffraction is likely to put a major limit on lens performance, and in anything less than strong lighting, low shutter speeds and/or noise are going to be problems. In other words, I tend to suspect that getting good birding photos with such cameras will be difficult / good results will be few and far between. But maybe I'm wrong.