Can you use the Pentax Papilio (or any binoculars) with a smartphone? Or do you need a dedicated accessory to attach the phone and lens together, as is available with the Pentax VM 6x21 WP?
Someone on Amazon reviews for the Papilio suggested using them with either the Carson HookUpz 2.0 Universal Optics Adapter for Smartphones, or the Celestron – NexYZ – 3–Axis Universal Smartphone Adapter for Telescope. But it’s hard for me to tell whether that’s another gimmick that won’t work well. Looks like the forum user at https://forum.inaturalist.org/t/homebrew-tech-what-stuff-are-you-or-would-like-to-goofing-around-with-in-camera-tech/38400/2?u=ukanuk had good results at least, although they also used a tripod whereas I was thinking of doing handheld.
I looked up the Ztylus Revolver, but looks like they only support up to the iPhone X and Galaxy S9. It looks like other people sell generic phone lens attachments though, Amazon has an entire category for better or for worse https://www.amazon.com/gp/bestsellers/wireless/15124502011/
Wirecutter reviews a bunch too (not just for iPhone in spite of the article title)
https://www.nytimes.com/wirecutter/reviews/best-lenses-for-iphone/
Okay, found a few other threads now as well after searching for “digiscoping”.
https://forum.inaturalist.org/t/new-to-digiscoping-w-binoculars/9966/4?u=ukanuk
“It is incredibly difficult to hold binoculars steady enough with only your hands, even if using a quality mount, to get a shot in focus with your phone peering through the scope lens. Best advice is definitely to get a tripod and adapter.”
https://forum.inaturalist.org/t/macro-and-telephoto-lenses-for-smartphone-cameras/9112/
Loads and loads of info