I recenly bought a Nokia 6300, not as a main mobile phone but because it includes Tethering, it is very light, changeable battery, practical as a mobile hotspot. It also has WhatsApp though.
Good to know! Thankfully, WhatsApp is just a minor detail in this context: tethering is the core feature. I'm curious, how has your battery performance been while using tethering?
Not for much longer.
I also got a Nokia 6300 to use for tethering and it works well for that.