Exodus Privacy will tell you what trackers are present in an Android app. They don't certify apps as "ad tracking free" but leave that decision up to you. The only certification of being ad-free is probably to be open source as well, in which case there's a large selection of apps in F-Droid which meet that requirement.
3) Turn off ALL apps, so when they launch they have no wan access.
4) Open each app one by one, noting what links and phoning home the app tries to perform
5) Watch in disgust as you begin to realize all of your efforts to secure your privacy up to this point has been in vain...antacids help.
6) Take control by granularly killing the links/calls in apps you decide to keep. Spotify calls FB, but you now can fix that. This is empowering but only a start.
R/privacy will make you paranoid, but a good place to get an idea what you are up against. I read Anon, join to post, and after some time delete my content, been doing that for decades now.
Looks promising, though it doesn't seem to have caught the FB connection in Zoom[1] (though given that Zoom has the Internet Access permission I suppose it can really send data anywhere?) They do offer an on-device version, which is available via F-droid[2].
https://reports.exodus-privacy.eu.org/en/