It boils down to consent. You should always always get consent before taking an action that includes somebody else. Just because you can see me is not consent to record me. If you don't have consent, don't do it. It's as simple as that.
Grouchy
Cell phone tracking is common place. If you carry one, you're being tracked, profiled and having your data correlated with others. The question is whether you support living in a surveillance society. If you do, grab a cell phone and be happy. If not, get rid of it and use alternative communication methods. It's a simple choice. In my experience, most people choose convenience over privacy.
You are correct. Streams is Fediverse software that you install on a server.
I initially misunderstood your question, so deleted my post. Sorry about that.
It defaults to config.hjson. Check the defaults.hjson file for a full list of options including the pool_size variable.
It's in the Lemmy configuration file.
Run your own instance. It's the only way you'll be able to set your own policies. Otherwise you're subject to policies of the instance you're on and those policies may change at any time.
Yes. Synapse is the server side part of Matrix. You install it at a Matrix host, or on a VPS, or even a Raspberry PI device. See https://github.com/matrix-org/synapse#installing-and-configuration
Once up and running you connect a client like Element to it.
Host your own Synapse instance and lock it down to your users.
It sets the maximum number of active sql connections Lemmy will use. Don't set it higher than what your PostgreSQL server is able to handle.
Setup a Koel instance at a host of your choice. Upload your music to it and stream from that. See https://koel.dev/
To use an Alphabet product is to support Alphabet regardless of how you access it. If you want to de-google, then stop using their products 100%.