Found this in the Google Cloud subreddit (technically, you'd want to put it in the G Suite reddit...but that's fine :P).
Two ideas:
First, get EVERYTHING into G Suite. Documents, calendars, all of it. That will be your staging ground for making connections.
Solution one: G Suite Cloud Search - search across all G Suite services, and also have some form of predictive analysis with documents you recently worked on and meetings coming up. Caveat is that it requires a G Suite Business or greater subscription (not Basic), so it costs $10/mo vs. $5/mo, though it also comes with infinite storage space and a few other perks.
https://gsuite.google.com/products/cloud-search/
Option two - use a CRM that pulls from G Suite data and makes connections for you. Prosperworks is a good candidate for this, though it also costs money. It's more for taking email and contacts and making connections for business purposes. Just searching across all the services for terms is more for Cloud Search.
I keep the absolute legal minimum of paper - business and personal documents. This amounts to a single manilla folder (licenses, certificates, state and federal required documents) for the family business and a legal folder for family documents.
Everything else is digital - either PDF (scanned) or original documents. Everything gets stored in the cloud (Google Drive + Google Cloud storage backup) and accessed via Google Cloud's Search that saves me tons of time - https://gsuite.google.com/products/cloud-search/
I don't use Android so not sure about that. You can definitely search inside Google Drive and Keep apps.
If you want unified search through all Google services, you can use their Cloud Search, but it requires G Suite business plan, which is $10/mo. On the other hand you will get Gmail on your own domain and pretty much unlimited storage, so it might be an option.