Material nodes with vector inputs have a default for those inputs (usually Generated, sometimes UV or Object). When I put together a Group Node it lets me set a default value for each of the inputs, but default value for the Vector input is three (XYZ) float fields. I can’t seem to set it to Generated or UV like other nodes have.
Without that the Group Node’s Vector input needs the output from a Texture Coordinate node (or such) to avoid being a useless single XYZ point. Which I’ll do if need be, and I have a reminder on the input’s Description. But if there’s a way to set the default to something useful like UV or Generated while still allowing it to function as vector inputs normally do? I’d like to know.
You could make a switch node group to default to object cords (or generated if you want).
There could be a better way (no compare in vector math node) but this one seems to work.
I added up x,y and z to see if the result is 0, I put the absolute vector to make sure the values are not negative. So if the input is 0,0,0 it will use object cords, there could be a problem were the coordinates include 0,0,0 but for the moment it seems OK.
IIRC this is more or less planned at least in geometry nodes, but I don’t think it’s there yet…
For now we have to stick with some hacks as @DNorman pointed out !
