When I did a quick glance at the FSA Gossamer Pro Modular AGX+ crank, I thought it was a three piece crank. But now I realize it too is a 2 piece crank. But it's made for wider BB shells and chain lines of what gravel bikes of late have been going to.
GRX cranks have that same 47 mm chain line. So going to GRX isn't necessarily going to do anything for you if your rear expects a chain line more typical of a road bike. So while a GRX FDR might give you the swing you need to reach the rings with the symmetrically spaced crankarm on both sides, then you still might have less than great shifting in some combos.
Seems the bigger issue is going to require you change the crank to something that want's that narrower chain line.
https://shop.fullspeedahead.com/en/f...ab79e2de27645/
https://shop.fullspeedahead.com/en/f...c298e69684883/
https://shop.fullspeedahead.com/en/f...847f3c9e4e882/