A bunch of AFCS systems revert to GS on approach in case of turbulence, even the bus. It's a fine reference for a minimum speed and the maths for wind correction isn't taxing. If you have nothing else then referring to GPS speed is an excellent idea and I've read it in more than one FCOM.
Here is what is says in my current QRH unreliable airspeed after pitch power initial items:
d) Check all available data sources, including:
• FMS, POS - GNSS for ground speed,
• FMS, POS - GNSS INFORMATION for GNSS ALT (if required),