> Some parts of the server were closed source for a bit. No longer the case.

In fact, nowadays there are many more closed parts in OM's map generator - many OM's bigger new features like hiking, cycling and bus routes depend on closed source improvements to the map generator. And some binary files required to build the app (e.g. packed_polygons.bin) are nowadays distributed under a custom non-FOSS data license. I.e. nowadays its basically impossible to fork OM as is with all its features - and the "right to fork" is a cornerstone of FOSS.

Also ref to: https://isitreallyfoss.com/projects/organic-maps/