Norway Nutshell experts : Is this feasible ? Oslo to Borgund to Gol by car and then train to Myrdal

I am thinking of arranging for a car to take us from our hotel in Oslo
to the Borgund Stave Church and then on the way back drop us off at
the Gol station on the Oslo - Myrdal line

Have you checked what that would cost and if it fits your budget? That sounds expensive. If you only want an hour at the church, the bus from Flåm to the church is a cheaper option.

I expect it will be expensive. But I dont have flexibility to do it from Flam. I can make my budget expand to the extra cost (there is 4 of us and train tickets from Gol are a decent bit cheaper, that helps a bit).

But is it feasible ?

Just be aware that when i say expensive, I mean expensive even by Norwegian standards.

Feasible? Yes, but it is a very strange itinerary and I'm wondering what you are actually trying to accomplish? You don't have the flexibility to visit Borgund from Flåm, but have no problem travelling from Borgund to Flåm via Gol and Myrdal?

Yes, because I will be in Flam in the late afternoon/evening and then cannot make it to Borgund before it closes. Even if I leave by 10:30 ish train from Oslo to Myrdal, I will only get to Flam by 4:30 pm.

My other alternative would be to rent a car in Oslo and return it in Bergen. But then I miss out on the famous train ride.

Your plan doesn't seem to allow for lunch. You can eat on a train but almost certainly not in the car of your private driver. An hour will be enough time to see the church but may be rushed if you want to make a complete visit to the stave church museum. Incidentally, you buy your church ticket in the museum building, so you need to stop in there first. There's food available in that same building; I think RS makes a positive comment about it.

Doing even part of the Nutshell itinerary en route from Oslo to Bergen makes for a long day, so I'm not recommending that you do the drive, but in the interest of full disclosure, plenty of folks off cruise ships do the Flamsbana round-trip. At least starting from Flam there used to be a bit of a price break.

You're going to miss out on the Naeroyfjord ferry between Flam and Gudvangen. Are you sure seeing the stave church is worth all that you're giving up? There's a stave church at the open-air museum in Oslo (which I haven't seen). The stave church at Fantoft (on the Bergen light-rail system, though a considerable uphill walk is required) is a faithful reproduction of the original, which was torched by some idiots about 30 years ago.

When are you planning this trip? There are also morning trains from Oslo that will allow you to be in Flåm by lunchtime.

Also note that the driving times shown on Google maps tend to be on the optimistic side.