I would agree that there will be thousands of devices that are currently compatible or in use with OH. That’s what the system is really famous for (beside lots of other things 
). And if you add those devices that are connected through MQTT, HTTP and TCP/UDP it maybe a hundred of thousands.
And maybe a database is the right place for that, yes. I don’t care about the technology or solution used.
That’s what I would call a typical technical/developer view. But e.g. OH2 is designed to have a much more broader audience than the more or less technical oriented user that is using OH now. And the first group mentioned would not go through every binding of that list of more than hundred to look if there’s a hardware he’s thinking of.
As an end-user I would rather look for a way to find a hardware for a specific use-case and then look what technology is used to connect it to OH.
So having a central-place where all hardware is listed and how it’s connected to OH would really be helpful. Of course this would never be complete. But hey, this is a non-profit community project.
So why not make the life of those guys easier? Those who put functionality and use-case before technology.
I think it will happen as it always does: if someone starts, more and more people will join and put their input in.
So. Any good ideas what technology would be appropriate?