Lipo Charger Shield. Directly plugs into Arduino Uno R3. Charge rate set with solder jumpers. Use with any MCU through tapping the VIN pin for power. VIN pin takes either

A multi-role sensor platform with some basic sensors onboard with plugs or solder holes for external expansion.

This surface-mount edge connector is designed specifically for the micro:bit. It's very slim and fully SMT. It also only has contacts on one side, just like the 'bit. This version is a Straight style where the micro:bit plugs-in perpendicular to the PCB.