Hi there, you should give Neeva a try. Disclosure, I work for them, but we were the first to introduce a subscription, interest/growth has been really strong so far. Neeva offers a freemium model (free basic and premium for $5/Month which includes paid versions of VPN and a password manager), you can connect third party apps like dropbox and email putting all your personal docs in one search along with websearch, both versions are ad-free and private, it's available to anyone in U.S. and we are building our own independent stack to make the search experience unique and better.

An alternative is academic institutions. I'd trust a university-backed government-funded search engine.