The issue is that we change our map file "format" with nearly every release, and handling that without crashing is already a job. For example if we add, say, bomb shelters to the map, an older app using that newer data will have access to it but no idea how to render it, which can cause problems (crashing, errors, blanks, etc.) So we have very specific versioning on a per-map-release / app-release basis, and that's just our project. We've already diverged from Organic Maps and even moreso from the (corporate, closed) Maps.me and living on a totally different data format planet from OsmAnd and Magic Earth. So it's a nice idea but extremely hard in practice.

There are converters between different OSM formats and other formats (Garmin comes to mind). It depends on the target. E.g. here: https://www.mapfileconverter.com/free-gis-conversion-tools