I like your idea. I wish I had a good idea how to start it small. Because, look at Wikipedia, it started as a small idea and look at it now!

Database sounds like a good idea. But when it grows the database needs lots of ressources (memory) which means money (as you said). So it would be tempting for the admins to monetarize it similar to Google, or?

A web directory already exists:

https://curlie.org/

You could help expand it.

I connect the phone with my computer (with USB cable) and copy the files (textfiles, PDFs, photos) to my computer and then to my backup drive.

I would love to read a wiki about degoogling phones. I am confused about rooting, changing the bootloader, custom ROMs, libre OS ontop of Android, etc.

I am still in the claws of Google. I use shitty Android (which is better than Apple). I use a Gmail account (and a self-run mail account). I use Chromium, but plan to pick a more lightweight, libre browser. I also plan to buy a Ubuntu Touch capable phone. [Edit: I use Duckduckgo.]

I don't feel too bad about being dependent of Google because I'm optimistic to replace it step by step.

I also had the idea of a federated search engine, but I have other stuff with higher priority.