Other measures that may be of interest to some:
ANDROID
Tracker- blocking apps like Blokada5, TrackerControl, etc. They do DNS filtering similarly to Pi-hole, except you install one of these on the device for protection wherever you go, instead of only at home. In fact, these apps can use the same public blocklists that Pi-hole does. (It’s also possible to set up remote access to your home Pi-hole installation if you want to.)
LINUX
OpenSnitch, (demonstrated by Kyle Rankin) is an on-device application that monitors your outgoing connections and allows you to enable or block them.
It’s available in official repos, including PureOS, and of course from the terminal (package name opensnitch).
I tried OpenSnitch on the Librem 5 last week and, while usable, it’s not completely adapted to the small screen. And as you often need to react quickly to popups, I recommend temporarily disabling the internet connection immediately after installing it, so you can scale it to fit the screen better (in landscape orientation) before the series of dialog boxes start popping up. Then reconnect to the internet to start using it.
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There are also VPN providers that offer DNS filtering, e.g. AirVPN, Proton VPN, and others.
Also remember that sneaky 3rd party trackers can be hiding in the 1st party domain, masquerading as native to the website.