I recently bought a Nitrokey Pixel Tablet and am now getting used to GrapheneOS. The reputation of GrapheneOS prompted me to buy the tablet and I've not been disappointed: the enhanced speed thanks the Google-free environment was quite a surprise! I've set as many apps as possible to not poll out for messages on a regular basis to keep everything as quiet as possible.
So yesterday morning I decided to install PcapDroid and see who exactly GrapheneOS and the apps were talking to. Yesterday evening I came back to find just over 20 entries on PcapDroid, and these were exactly the ones I'd expected. A few DNS queries, a single Caldav calendar update, a couple of mail polls, a GrapheneOS update checker; nothing controversial. Very impressive indeed.
Contrast that with my Samsung A25 phone (stock Android 14) which in 10 minutes has already registered 100+ call-outs, mainly to Google and Samsung. The "privacy-centred" Brave browser is also a lot chattier than I would have thought and I've come to the conclusion that if I want real privacy, GrapheneOS is the way to go.