Well I may as well answer my own question with the research I've done thus far. First, it appears that even privacy advocates just use Google Firebase. (Yeah,

Well I may as well answer my own question with the research I've done thus far. First, it appears that even privacy advocates just use Google Firebase. (Yeah, hypocrisy is abundant.) Matamo.org is the top contender I found for privacy-conscious analytics. Basically, you have immense control over the integration, so you can accomplish any privacy goals you'd like. Other potential analytics tools (not necessarily privacy-conscious) include segment.com and Mixpanel.com. Many of the other ones were recently acquired by Google and are now shutting down.