I have some trouble with abstract concepts, and like conrete examples.
Assume a test case: I found a litttle KiCad project on Github.
It has a schematic of a small SMPS circuit, and a carefully layed-out PCB according to EMC guidelines etc.
(LM7805 is too trivial as example).
I like the design and want to use it as part of a bigger project.
(Is this the sort of thing you are thinking about?)
The schematic can (I think) easily be copied or included as is as a hierarchical sheet.
I think that part is already in place.
The PCB part (component placement / traces) is harder I think.
I would not know how to do that now.
I may attempt to make my first panel from 3 PCB’s in the near future.
I read something of opening Pcbnew in “stand alone mode” (not from the project manager) and then importing boards. (Have to experiment with that).
If that works well then the same method can be used to import the traces / components of that sub circuit in your current project. I.e: Open Pcbnew standalone, import components / traces. Save. Open as a normal project. delete / edit board outline and continue with the project. You may want to make little adjustments, such as a different sized inductor for this SMPS circuit.
Part of it is probably the Chicken and Egg problem.
Without a database, no projects get collected, and without projects it’s not worth creating a database.
You can find KiCad projects on github and on other places on Internet, but those tend to be complete and more complex projects.
Aisler has some 200+ projects collected, with various amount of documentation & (often?) github links.
Oshpark also has something similar:
Unfortunately ospark offers only gerbers as downloads or you can order boards. No documentation or (github) links or even schematics??? I do not like this idea. It seems to be designed to reap the crops from other people’s efforts.
You could browse through those PCB’s and try to find more info by copying the project name into a regular search engine or github, but it seems more trouble than it’s worth.
There is no guarantee these Aisler / Ospark hosted projects are even made in KiCad (or Eagle) but with the fast improvement cycle of Kicad this ratio can only improve.