Thanks for posting that, chris.
FWIW I noticed this question sent to L Zinn re just this issue:
… from a guy experiencing some issues running GRX FD with road-like chainline crankset. Maybe it was a setup issue, contrary to what the fella though? Personally, I think I’d prefer to play it safe though and I’ll try to retain GRX FD and cranks, per the Shimano “advice”.