I also had only 2 sites/apps. One I used Facebook oauth, the other I'm not 100% sure what it was.

My strategy (Desktop & Mobile):

Firefox + Facebook Container & uBlock Origin & Privacy Badger & DDG as search.

For me they have nothing (success! :)

I use Firefox + FB container + uBlock Origin + Privacy Badger and recently started to use CanvasBlocker as well. I have Firefox configured to delete all cookies on closing (except for few sites to avoid the need to enter the 2FA code every time I log in).

I've also set Firefox Enhanced Tracking Protection to "Custom mode" with "cross-site and social media trackers" blocked [1] and to use block list "level 2".

I also have the "Do Not Track" option switched on.

I don't have a proper smartphone (never owned one), just KaiOS-powered dumb-phone on which I use Facebook mobile (i.e. their web site) all the time.

Also no Pi-Hole or similar stuff.

I use a throwaway email account for Facebook.

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[1] Just now I've found out that there seems to be a new option, to disable "all cookies from unvisited sites", which I'm going to try as it looks even better.

> I use a throwaway email account for Facebook

I feel like this might be key, I use a random burner number and this seems to confuse the tracking.