I am getting ready to use a spunding valve for the first time and have a question. If I transfer from primary to a keg with several FG points to go, will there be enough yeast to continue fermentation?
Should be, if you are confident in that FG.
Brewing software will make WAGs. If you pull a sample 24 hours after pitch and let that stand or swirl it at warmer temps, it should give you a reasonable expectation of FG. If you put it on a stir plate, it might over-attenuate a couple points, but with practice you can anticipate that.
Good luck! Spunding gets you carbonated beer faster