If you want one that can survive anything life will throw at it, look at the Sonim devices - the XP3+ (flip) or XP5+ (candybar). They're Android Go, have exceptionally good (week and a half, easily) battery life, hotspot just fine, and handle actual use a lot better than the KaiOS toys out there. Maybe 3.x is better, but KaiOS 2.x couldn't handle actual use for more than a few weeks without starting to lag, requiring you to remove texts from it so the interface wasn't glacial, and mine eventually just stopped bothering to notify me about incoming calls and texts, which is your one job... The Android Go stuff seems to actually hold up to sustained moderate use.
Assuming you use something like WhatsApp, Facebook or something alike. Modern "feature phones" include built-in applications for messaging and calling, and you generally can't install anything custom on them.