Strictly speaking, I believe HTC don't have the info they need/want for the 4x50kg centerline rack. They asked for some info from the community back when the 109s were being redone, but didn't get what they wanted. That's why our 109E has no bombrack options and possibly why our 109F is a pure fighter.
Since it is the same rack, and they are still lacking what they want/need to know, it stands to reason that's why it's not an option on the Fw190F-8 either. I presume/guess that if/when it's ever added to the 109s, it will be added to the 190s at the same time. It won't require a new variant, and would just be a loadout option on the planes we already have.
Strictly speaking, though, 50kg outboard are pretty useless, even against towns. You need salvos of them. Nice to have as an option, but a single 250kg is better because you'd have to drop 2x 50kg anyway to get a kill on any building, and the 1 bomb packs more than the 2 lesser ones.