The F9P is accurate to about 1.4cm, for 10mm or less you’ll need to look at some of our other models like SparkFun Allband GNSS RTK Breakout - mosaic-G5 P3 - SparkFun Electronics
The 290p might also be viable if cost is a priority over accuracy SparkFun Quadband GNSS RTK Breakout - LG290P (Qwiic) - SparkFun Electronics
You’ll need an antenna - are you going to be using a surveying pole? The antenna chosen will need to be compatible with the L-bands listed for the receiver…for the X20 I’d get GNSS Multi-Band L1/L2/L5 Surveying Antenna - TNC (SPK6618H) - SparkFun Electronics (antenna quality can greatly affect result accuracy)
On each product page there is a ‘documentation’ section with links; the hookup guides in this area will walk you through getting it set up and going once in-hand