Employee snacks can be a surprisingly contentious topic! It's hard to please everyone, and the more people there are, the more impossible this becomes, but in terms of keto, you have some fairly easy options:
Charcuterie boards. Often you can find these at grocery stores, ready made. Sometimes they have non-keto friendly items in them (jellies, crackers) but as someone who does keto I'd be happy to let my coworkers handle the crackers and jellies and I'll stick with the meats and cheeses.
More breakfasty: crustless quiche. Quiches are almost always keto-friendly, with the crust being the problem. Keto (or low carb dieting in general) is fairly popular these days so you can likely find some crustless quiche options around you.
There are plenty of other ideas out there for keto snacks (I also like pork rinds with a creamy brie dip, or whole milk greek yogurt and blackberries) but the charcuterie board seems like a best bet (if you have people doing keto and people on vegan diets then we'll have to call in some experts and make Venn diagrams.)
Be wary of fruits, veggies, and dips unless you want to spend time scrutinizing them. Half of doing keto is snacking on something, reading the label halfway through and going "Oh" because you thought it was low carb but actually was not.