Lineage is a decent option, but ultimately there is no such thing as online privacy. Aim for anonymity instead.

Compartmentalize and separate your personal stuff from any KYC apps. Use disposable second hand smartphones and don't spend too much time thinking about tinkering with the OS -- diminishing returns and many unknowns.

In summary, don't stand out and keep things separate.

CalyxOS is an alternative. Don't know if it's any good though.

I think @DartCoin uses another OS that is compatible with more phones. You should ask him. There's also the Pine option. There was a post on here recently.

DivestOS is suggested among people close to the GrapheneOS project. It is essentially LineageOS with some GrapheneOS patches and a focus on using minimal proprietary components.

A lot depends on what kind of phone you have. Many privacy-oriented ROMs are specifically designed for Google Pixels. If you don't have a Google Pixel (which I deduce from your search for alternatives to GrapheneOS), I recommend installing any ROM that doesn't come with pre-installed Google Services. Among popular ROMs, I suggest LineageOS or VoltageOS (which I personally use due to its interesting features not present in LineageOS). If you're looking for something built with privacy and security in mind, I recommend DivestOS (a fork of LineageOS).

Regarding installing apps on an Android without Google Services and the Play Store, there are two popular alternatives: F-Droid - This is a store where you can find open-source applications. Aurora Store - It's an open-source client for the Play Store that doesn't require Google Services for operation and doesn't require logging in.

Before buying a Google Pixel 6a I was considering getting a Fairphone to use it with LineageOS. That might be a viable way to go for you?

I use CalyxOS, but it still requires a Pixel..

Nextel

Theres also this https://e.foundation/e-os/

I understand this dis-trust of Google. Bottom line to consider is that you are always trusting someone unless you build your own devices, manage your own network, build your own software. I'm not trying to talk you out of this because I would love to see other phones supported besides those made by Google. Its probably the biggest issue with de-googled phones. Google could break these privacy roms if they wanted to. I don't see that happening in the short term but they could do it. I also believe that if they started doing things in the chips to track people, security researchers would find out and report it.

Be careful that you don't buy some cheap crap android device that is made by some no name manufacturer thinking you've escaped the eyes of the watchers. Most of the privacy issues are not hardware issues. The apps and the OS are the main issues.

I would suggest that get your device codename and search for available Custom ROMs built by the community on TG/ XDA forums (Which are tested and then uploaded by them)

There are tons of Custom ROMs out there you can explore. And also, you can make your own ROM if you don't find your match (Not much of a code just cherry-picking stuff and a machine to build it).

What's wrong with Graphene? You can't take credit from Google hardware engineers, it's a darn good hardware. Google spy Software is what sucks, so Grafphene replaces it. It's like installing linux on intel x86 that was primarily designed to run windows. Hardware good, software bad... replace bad. Just my 2 cents

They run on Pixels because that's pretty much the best phone in terms of security and privacy.

You can read here some of the properties that a phone should have in order to be able to run GrapheneOS on it. Here's an excerpt:

Why would an alternative not have backdoors but the pixels, the most private and secure phones, would have them? Makes no sense to me.

Sailfish OS? Native Linux OS, instead of Android bullshit. Original MeeGo by Nokia and Intel, which was killed because of politics not tech back then.

LineageOS is an option. There is Ubuntu Touch as well. There is SailfishOS as well.

BTW: I made this post about Linux pre-installed mobiles: #226965

If you change the software /OS.....it doesnt matter what "backdoors" are on the hardware. Software is what tells hardware how to act.