I would recommend GrapheneOS. There are literally no Google dependencies at all. They have reimplemented privacy friendly alternatives for all built in functionalities typically depending on google such as for location.
Additionally, with their custom built compatibility layer, they allow you to install google play services as a regular app, and fully control which permissions you grant it, which can be useful for apps which depend on google to give you notifications.
Grapheneos is also at the bleeding edge of speed to deliver security updates several times a week.
And with user profiles you can fully separate apps yet they have a custom way of piping notifications between profiles as profiles is a particularly convenient way to isolate apps and prevent them from knowing what other apps are installed.
It's not perfect but it's definitely the most secure and most privacy respecting, it's user friendly, puts the user back in control and works really well the moment you have adjusted to the new way of using android and make use of all the features.
Edit: big caveat, it is only supported on Pixel devices, which may seem illogical for an OS getting as far away from google as possible, but it's for their good security hardware, driver support and allowance for installing an alternative OS.
I'm glad I picked up a second Pixel 6 at a good price, tried GrapheneOS out on it and I am slowly turning it into my daily driver.
I couldn't be happier with it so far, battery life seems better, I feel more like I "own" the device and that it isn't up to sneaky shit etc.
It was by far, the easiest OS install I've ever done, I hope they keep up their awesome work.
Now I just gotta find a good OS for my tablet.
I understand your frustration. I bought a second hand pixel 6 specifically for GOS and couldn't be happier.
Started with a pixel 5 but hated that device due to its poor display design where the display wouldn't stop popping out of the chassis and the earpiece which needed contact to the display would just disconnect when the display was out and the audio quality was bad.
I personally recommend the pixel 6, it's a good device. It still has guaranteed security updates until at least October 2026 and can be found for rather cheap on the second hand market.
If you can afford to keep your phone until you figure out whether a pixel 6 with grapheneos is a good fit for you, I recommend that option. You can then later sell it once you're more familiar with the new ecosystem.
Otherwise, it's a bit of a bet. It depends on how confident and familiar you are with privacy compromises, though grapheneos doesn't force many compromise on you as you can always install the google play services if you need push notifications for WhatsApp for instance (though in that case, I would suggest installing WhatsApp with Google play services in a dedicated separate profile and "pipe" notifications through to your main profile).