Actually, I started thinking of a door yanking+grenade breach maneuver just after posting. The action’s speed and accuracy of the toss could be affected by skills and/or perception/dexterity.
Further down the line, it could be possible to drop grenades out of windows. Of course, Z-level vision would most likely need to be in place to make that feasible.
On the subject of breaching, what would be the possibility of sticking a grenade in a funnel and placing it on a metal door? Shaped charge fashion? Could require an adhesive and a string to make it work. Cheap, but one time use and LOUD.