I was thinking the same, and it is!

Edge Connectors Pin numbers are compatible with micro:bit, 19 independent I/O (Support 1 ×I2C, 1×UART, 2×SPI, 6×12-bit ADC, 5×10-bit PWM)

https://www.unihiker.com/wiki/specification

Note: The edge connector on the back has no electrical connection.

https://www.unihiker.com/wiki/board-overview