FitoTrack is a nice open source fitness tracker which shows the path on OpenStreetMap background. It logs position and speed data.
You can create a custom workout which shows you the current speed instead of average.
https://f-droid.org/packages/de.tadris.fitness/
What do you actually need it for?
FitoTrack may be suitable for that.
If the Map is not fitting totally you can even correct it on OpenStreetMap.org by yourself