Decision matrix for small MCU with onboard WiFi

My contribution:

My first Arduino project (and most challenger untill now) was a Bluetooth scale that I did for my wife.

I´ve started with an UNO + HC-05 module. Then dowscaled it to a Nano 33 IoT, but found it difficult dealing with Bluetooth Low Energy.

I ended up using this ESP-32 with 18650 battery --> http://www.lilygo.cn/prod_view.aspx?TypeId=50033&Id=1170&FId=t3:50033:3

Nano 33 IoT also has a built-in wi-fi, which would fit your requirements, but it´s also a 3.3V based board.

So, IMO, keep going with your ESP32 Huzzah.