There are several possibilities:
I am blind
Its too trivial
its not possible
its only for insiders
…
I just cannot figure out how to use a generated object in another project. i.e. to set up a library of objects (trees, stones, faces,…) as *.blend files to integrate them later in other projects. Append seems to import always just one special property. And other way round to export one object or a group of objects to another *.blend file omitting everything else (e.g. scripts).
As I tried to state: Append dives into the properties tree and allows to select one property and not the whole object with all its properties (texture,…). What I am looking for is something equivalent to selecting an object, mark it for copying and paste it to another project.
I find it very useful to keep a blend file of objects with materials I like. I append all or groups of materials into my working file. It saves a lot of time.