Quite a few of the dumb phones have WhatsApp. Although the maps experience would suck.
Personally, since they already have WhatsApp, having a good camera and 5G tether are my two wishlist items. 4G tether is probably fine for the most part but the good camera would be missed.
That with an iPad mini, so that I can still use banking apps and maps but I’d have it in a bag so that it’s not simple to access and I could leave it at home would be my ideal.