I think that using gecko based browsers like Firefox is the best thing to do in the short term. But having no competition is a bad thing. So supporting new web engines, like Ladybird, is important too: https://github.com/LadybirdBrowser/ladybird
Thank you for your comment. Since I deactivated Google Play services, I don't get notifications on many apps. I didn't know there were alternatives. Unfortunately, the app server must be compatible, but if I can have it at least for Telegram with this fork, it would be a good start. I'll take time to compare the different alternatives and see if other push servers are compatible with more apps.
For what I understand, there are self hosted push servers, like NextPush that works on Nextcloud, and some that provide you a server, liked ntfy. For the latter, you have to check the privacy policy to see if it's better than the default Google firebase server.
I don't know if there exists such a thing as GrapheneOS account, but it is not required. You can add Google, Facebook or other accounts like with regular Android. I use a self hosted Nextcloud instance to synchronize contacts and calendar with DavX5 app. GrapheneOS has built-in apps. I use most of them. For the app stores I mostly use Fdroid and Aurora store for non open source software. I don't use Google play store even sandboxed because I don't accept the terms of use, mostly because they have the right to uninstall apps from your phone without consent or notice.
Some like Phind or Perplexity cite their sources. And they give you directly the answer you're looking for without having to search it in a mess of "subscribe to our newsletter", "other articles that may interest you", 3 paragraphs of "if you read this article, you will know what you want to know", "special promotion for you",…
The announcer (the enterprise on the ad) pays to the advertising platform (for example Google) which gives a small amount to the site displaying the ad.
Use cash. A card payment allows your bank and the shop to track you.