I'm sorry to have caused so much trouble here.
That's hardly your fault. People tend to have strong opinions when it comes to technology, which naturally leads to clashes.
I'd like to move to GOS but, given my circumstances, I'm not sure if it would be an upgrade or downgrade in terms of overall privacy.
I used iOS for the past 10 years and moved to GrapheneOS last month with a Pixel 6a. My advice is to buy the Pixel 6a, not the Pixel 6, as you get a year more of support, and the size is most similar to iPhones. I'm quite happy with the experience. The people I was messaging used Android anyway, so I was SMSing them through iMessage. Little has changed for me, except I can now backup my Signal conversations, I have better battery life than my iPhone 8, and I trust my phone more. GrapheneOS also offers stronger security guarantees than iOS—have a look at some of the features. For one thing, Chromium-based browsers are more secure than browsers using the Webkit engine like Safari.
As for privacy, if all of your contacts use an iPhone, iMessage is more private than SMS messaging on Android for most threat models. If any of the people you're contacting move to an Android phone, they will be using SMS, which offers no privacy improvement. I would say iMessage's superiority in privacy is a precarious one designed to lock you in. These communications are important, but so long as you are aware they are not private, you might choose to say some important things only in person.
Who knows—maybe your contacts will be so annoyed by the lack of MMS capability that they'll offer to message you on Signal? This isn't my experience, but you can always hope.
Escaping from Apple has been a liberating experience. iPhones are hard to integrate with any of the other technology I own, so every time I wanted to extract photos or get files onto the phone, it was a harrowing experience. My Pixel 6a, on the other hand, connected right to all of my computers, offering at least two easy methods of transferring files, with transparent access to the filesystem. I also don't need to use Google Play if I don't want to—I can download APKs directly from the developer and manage updates with Obtainium. I don't even need to use a proprietary version of Android or iOS on my phone. I can use a free software operating system like GrapheneOS which is aligned with my interests, not Google's or Apple's.
Privacy is one of my top concerns, but sovereignty is another. Apple might offer you privacy, but they only offer it to you on their terms, and with caveats. If you're using an Android phone, you are not worthy of privacy in Apple's eyes, and they refuse to develop even a basic iMessage client for Android or provide Android developers with the ability to develop their own.
I really have no idea what sort of data Apple is sending to themselves every few minutes and it bothers me that the iPhone is constantly communicating with Apple even when I'm not using it.
GrapheneOS will not do this. Google Play Services might communicate with Google's servers, but you can choose when and how you use it by installing it in another profile. If you don't need certain apps only available on Google Play, you can eschew using these apps at all.