Let's not derail this into an Apple vs Google battle regarding privacy. I think we can all agree that they are both horrible in their own terms and GrapheneOS is much better in both security and privacy. The project homepage will give a lot of information about it.
Kilsnacks welcome to the community, nice to have you around! Unfortunately iOS is indeed bad for privacy, and so is Google. I recommend you watch this fantastic video by TheHatedOne to understand why that's the case.
Now the bad news are that most of your desired features are inherently compromising privacy for convenience and there is not much you can do about it. For example: For a find my phone feature to work, some service needs to be able to track your phone 24/7. Even if you find an open source, self hosted service for this, it would require either privileged access to your device or for you to constantly keep GPS and mobile data on in the background. Both are bad for privacy and security. At least that's my understanding of the dilemma.
The good news are that you might find some workarounds or solutions with acceptable convenience tradeoffs (like the Pixel Watch for payments). If it works for your budget, I'd recommend getting a cheap current Pixel phone (probably a Pixel 6a), flash GrapheneOS on it and see if you can get used to it. Once you can leave your iPhone at home, you'll have a much more secure and private solution. And if you figure it doesn't work without the iPhone, you probably want to choose one of the two next best things regarding security (as privacy is not available and only worse on other devices): iPhone with iOS or Pixel with Pixel OS. The first one is better integrated, the second one gives you added flexibility (as shown in the video above).
I also recommend you take some time to make a more detailed threat model for yourself, as only you can assess what's important to you. It will help you find the right answer much faster.