Further to Tony's answer, the rule of Fusiliers not wearing bearskins on campaign had been established prior to the Egyptian campaign, having been seen in both the SYW and the AWI (in the latter, all three Fusilier regiments had worn normal/adapted hats in the field). The Foot Guards, of course, had not started wearing bearskins for all ranks in all companies, and would not until after Waterloo anyway.
It's difficult to know for sure whether any grenadier companies took their bearskin caps on campaign at this time, although by 1800 all companies would/should have been wearing shakos with coloured feathers anyway. We do know that they stopped wearing bearskin caps in the field about mid-way through the AWI and went to hats (which all flank company men received as part of their annual clothing allowance anyway, in addition to their "specialist" kit) with white feathers instead. However, whilst numerous "field mods" from the American war became official policy from 1785 (eg grenadiers losing the matchcase off their cartridge belt and their characteristic short sword) it cannot always be assumed that anything done in America automatically applied in other theatres.
That said, if your troops are in shakos, I would include grenadiers in that, for all units even the Guards; troops from India might have been wearing earlier uniform styles, but centre companies would certainly have been in round hats, as would troops from Minorca and other Mediterranean garrisons.