I personally use a paid E-Mail service (mailbox.org) and a self hosted nextcloud.
The APP myphoneexplorer can be used to sync offline.
This can be quite difficult to achieve. The moment your contact information is given to someone using Android, it will be synced up with Google (and known by most Google properties).
> I personally use a paid E-Mail service (mailbox.org)
May I know how long you’ve been using it and how the experience has been? Are you using it with a custom domain?
Disclaimer: I use this email only for friends and family, told them not to tell anybody and did not register ANY internet account with it - so no spam, no unwanted emails and no shit.
I guess it won’t tell big tech who your friends are. At least until you talk with them regularly through online channels.
- phone - this is kind of ok, because phone spam is less common
- email - to prevent spam
- birthday - this one is quite critical, because here in germany it is a common way to verify authentication on phone calls by insurance companies
- job-details, contact relationships, etc.
I doubt that these are all in the public registry.