There will be shortcuts. Now I’m only a little into Steamworld Dig 2, having just bought 1&2 in the last month myself, but in 1 there were teleporters you could buy and place at will, for a resource cost. But these would take you back to town. There were also elevators for direct access. I have to imagine that there would be similar mechanisms to limit the 2 of backtracking to sell loot.
Like you fairly early get access to a pneumatic tube which provides instant transport back to town, and returns to that location from town. So the level of backtracking should stay fairly constant and never exceed more than a minute or two of time.
Unless they radically altered that for 2. Which would be unusual. It was a smart design choice in 1, there was backtracking to sell loot, but it was always a very reasonable level.