Hi, Sebastian! What I like about your comment that you are not saying that it is impossible.

About small COS community: how large the community should be in numbers to support the project in your opinion?

In my opinion, 3rd party library for InterSystems data platform would be supported by the community if:

1. It provides a great added value for significant part of community

2. It is easy to collaborate in development

3. It is easy to install/deinstall the library

I would add that repositories with "separate files for separate classes" and "Packages are folders" approach are much more readable if the code is exposed in UDL form. Check cacheobjectscript-udl repositories with code in UDL as examples. 

Atelier supports UDL and there are several libraries like this one which allows export Caché objectscript code in UDL easily.