Thought I'd be an outlier here, but the themes in the comments resonate with what my 2 cents would be.

The biggest change was moving to a phone that ditches all Google Play services. This included microG and other variations. The only play services emulator that is running is https://github.com/lukaspieper/Gcam-Services-Provider, which doesn't do anything really but simulate the presence of google services for the google camera to work. You can navigate the source, it's really short. I use it to get the Google Camera working.

I got a Pixel 2 a couple of years back and more recently a Pixel 4a. Then I installed Graphene OS (you can run that or Calyx OS, people might get into heated discussions, but for the purpose of this, you would install either of them with nothing Google related anyway, it's just whatever is completely stock and barebones).

Once you're at this point, you are forced to change your behavior, so the choice goes from "which of these apps should I use as there are SOOOO many of them" to "which apps do I need to add to the phone". After a few months I'm down to:

Signal, Fennec, Aegis, Mullvad, Tutanota, Termux, Unlauncher, Gcam port for my phone, Organic Maps, Syncthing. The background is black, the font is red. A big shoutout to all the persons working hard on all of these applications, do support them through donations or any help you can give them btw.

To get here I had at a point microG, google maps, YT Vanced, Dropbox and the usual slew of things, but I still kept picking up my phone and scrolling mindlessly. I think this is the first thing you should do. I know people might suggest going outside, watching movies, subscribing to your favorite blogs and other things like that, but the reality is, you need to change the association you make with your phone first. This goes for all your devices btw, not just your phone. It needs to revert back to being a tool that obediently sits somewhere away from you and is picked up to perform a specific task and then put down again. Constant entertainment shouldn't be our goal in general, but I digress.

Once you get the change (you can pick up older Pixels pretty cheap used - which is also great for the environment btw!), the next step is to look up 3-4 sources of information (I go with 2 or 3 that lean the same way I do politically and 1 that is the complete opposite) and assign let's say an hour in the morning or one in the evening when you might go through those articles.

I afterwards realized that nothing really changes by me going to several places to look up things. It doesn't matter if you read about something on CNN/Fox/The Guardian/The Atlantic/BBC/Al Jazeera, at the end of the day, it happened and 5-10-20-40 different sources will really talk about the same event. Will this event impact you? Probably not. If it does, i'd recommend you look for a source of news that's closes to you geographically, they might have some more localized insight. Chances are if cycling legislation changes in Berkeley, a local website/paper might have more relevant information than Al Jazeera (which, chances are, won't cover that event anyway). So this was the next step, once you start weaning yourself off of the endlessly repeating news cycle, look for something closer to you. Maybe at this point, you can do a quick read over some of the big topics once a week - how's the humanitarian crisis in Yemen? Is there anything you can do to help (pressure your elected officials/gov/etc, join an NGO and help that way)? This is, in my view, essential to being a good citizen. Once that's done, you can check maybe what happened locally, which will, invariably, impact your life to a greater degree than what happens half-way across the world.

First of all, congrats you're still here, you're doing well!

At this point I check HN a couple of times a day (this is one of those occasions), I look for anything that I'm interested in, try to limit it to 2-3 articles and that's me. This whole process probably took around 5-6 months from start to finish. The slower you go along with it, the better chance things will stick. I feel a lot better now than I did a few years ago when I was one of those people with a couple of screens of apps. I have more time, I look up what I'm interested in, I feel more connected to my local community and my local government. I have time to research a topic I'm interested in with greater focus instead of being devoured by a slew of panic inducing titles or gifs/videos that keep me scrolling endlessly.

We (and here I mean most tech/knowledge workers) are stuck in front of screens all day... We should by now have figured out that when they aren't helping you, they are DEMANDING your attention and they give very little in return. So the best mentally healthy apps are those that you don't use. Those that you uninstall and those that give you time back. Sorry for the long rant, hope it helps!