I didn’t find much information about the dried fruit used on the trail.
I did find that dried apples were used quite a bit.
The kind of fruit brought along would have depended on if they could get them.
They were on the trail starting in either April or May. They landed at home anywhere from August to October. Walking alongside of wagons for 2,170 miles doesn’t make one want to get creative with food. The hot summer days had to be taken into consideration when the travelers bought food in Independence Missouri at the start of the trip.
Unless there were berries or fruit trees along the way, they had to eat whatever dried fruit they brought along.

Two maps to start.

Oregon Trail Map  by, National Park Service

NASA Topographical Map with red line  by, Mathew Trump, Wikipedia Commons

The next four pictures are from Wikipedia Commons.

Currents drying  by, Robert Wallace

Raisins  by, Scott Ehardt

These are dried apricots, pears and prunes  by, Andre Kawath

The last picture is of dried apples  by, Matthew Deute.