It's a good question, Wally, and your thinking is logical. I used to do a lot of research on the SYW and as far as I remember, it works like this.
Firstly, most armies in the SYW had their Grenadiers combined into consistent battalions on a semi-permanent basis. Prussia of course, but also Russia (in addition to actual grenadier regiments in this case), Britain (SYW in Germany) and also almost all German states. In this case there were battalion guns allocated as for line battalions.
In the case of France, grenadier battalions were never formed on this basis. (Yes I know there was the unit "Grenadiers de France", but that's really a line unit although formed long before from the grenadiers of militia regiments or something.) The French infantry's grenadiers almost always remained with their parent battalion, forming up on the right, or most exposed, flank. On particular occasions some grenadier companies would be combined for a very specific purpose on a small scale, eg at Hastembeck, Chevert's flanking column was headed by 12 companies of grenadiers, equating to about a battalion. Such temporary combinations wouldn't have battalion guns attached.
The awkward case is that of Austria, and hence of Austrian-commanded Reichsarmee infantry. Their practice had been along the French lines, but increasingly during the SYW, there were some battalions of combined grenadiers, used either as in the Hastembeck example or to form a modest number of battalions to comprise the infantry part of an army reserve. So did they have battalion guns? Sometimes, perhaps is all I can say, I'm afraid!