Just to add my 2 cents
Imo a “kosher” phone and a “dumb” phone are not the same thing;
Kosher means that it’s content is halachicly permissable, and in this gufa there are obviously different shitos, some will say only talk and text, some say a whitelisted browser is kosher, some will say not, etc.
“Dumb” (and by contrast, “smart”) are terms describing how accessable the device is. There is no “this is a smartphone” or “this is a dumb phone” (בענין obviously, lpoel there are commonly used terms) rather “this phone is (maybe even incomparably) smart*er* than this one.”
There is your classic Alcatel/tcl flip phone, which most will say is dumb, but then there is one with only 3 buttons, even dumber. Then there is a qin/fig/wonder, touchscreen android phones, but smaller, and by consequence, less addictive then a “smartphone”.
Personally I would call a Sunbeam a “smart dumbphone” and a qin/fig/wonder a “dumb smartphone”
Then you can have a non-kosher (to your standards) dumbphone, or a kosher smartphone
Sorry if you don’t agree, just my opinion
Some might have said this, didn’t read the entire thread.