In the in-browser version, it should take about 2 minutes for 1 point.
In the full version, it should take about 8 hours, as per the original game.
Im using the rom on a fpga gameboy core. https://github.com/MiSTer-devel/Main_MiSTer/wiki
The rom version is the full version. You need to play for 8 hours straight to get a point. That's a point counter, not a mile counter. It doesn't go to 1 until your first point, after 8 real time hours.
You can download the "short" rom instead, in which case you'll only need to play for 2 minutes in order to get a point.
Code's here: https://github.com/ekimekim/desertboy
It shouldn't be too hard to add a second counter sprite that updates based on the distance travelled variable each frame, but you'll have to do it yourself. I want this version to remain in its original state as of the end of the Jam where I made it.