Honestly?
No. I'd say they can't. Truth is, Fire & Fury is based on big games.
Whether it's the Brigade version or the Regimental version, the base count is just the same (if you like, in the Brigade version a base is a regiment, and in the Regimental version a base is a company - not exactly, but more or less).
I'm sure someone will say you can play F&F with a low number of bases but, truth is, you won't be getting the best out of the experience. It would be leading you astray.
One option might be to try Osprey's 'Rebels & Patriots'. That has a figure count of about 50-60 per side. Can be played with either 15mm or 28mm. Figures are individually based, mind you. But you could multi-base them and mark casualties or, as your collection grows, you could just ping them off whatever bases you have and re-base them as units?
That'd get you going nice and quickly.