I use Ansible + Vagrant for development env only and for some times to test on different env too like staging etc.

I try to shift my env to docker but faced alot issues in configuring and running some scripts on docker-compose up.

What if we sync account on Firefox, how much Firefox use our data?

See https://accounts.firefox.com/legal/privacy which links to https://www.mozilla.org/en-US/privacy/

But in practical terms, I am not aware of any uses of the sync data apart from actually syncing it. That is, no mining of that data, etc.