Can I rent a car from Voss and drop off in Bergen or vice versa? OR any other places? Looks like there is no one way car rental options is that right?
Most take the train. Travel in Norway is very expensive on the ground.
We took the Norway in a Nutshell tour where we took a train to Flam, another train down into the fjords and then a fast ferry out to Bergen. It was a full day's journey, but very enjoyable.
There are four agencies in Voss including Hertz. When I looked into a one-way rental two months ago between Bergen and Alesund, it was more than $1,000. We decided to fly. It looks like Hertz in Voss will rent their least expensive for one day dropping it off in Bergen for $411.
Hertz has an office in Voss so it should be possible. Otherwise you can always take the train as mentioned.
There's also the once-a-day (I think) express boat from Balestrand to Bergen. That doesn't sound like a good substitute for the Naeroyfjord ferry, but you're already planning to take that ferry, so using the express boat for transportation might be worth considering. I don't know how much it costs, but it's a pretty common solution for folks who opt to stay in Balestrand, since the rail line is on the opposite side of the Sognefjord.