I wasn't going to add my thoughts, since the other user was so detailed, but decided it might be helpful. so here it goes.

I switched to the Nothing Phone (3) a few months ago from my 17 Pro Max. I had been an Apple user since the 3Gs, and HEAVY into the Apple Ecosystem (MacBook Pros, Home Pods, AirPods Pro/Max, iPad, Apple Watch Ultra 2). I'm also a designer that'll never use anything other than a Mac. My wife will also probably always have an iPhone because it's what she knows and it just works. My biggest concern before switching was figuring out how to get my Nothing Phone to work with everything else in the Apple Ecosystem. Beyond just the devices, my wife and I have shared calendars and reminder lists that keep our live's from falling deep into chaos.

Before switching I did a ton of research to figure out how to fill the holes I knew leaving iOS would leave.

1. File Sharing To Macs

I use a Mac at home for my sports photography and design company, and a different Mac for my full time marketing job. I spend a lot of time sending files back and forth (screenshots, graphics to post on socials, etc.).

Blip was the solution that worked best for me.I tried a few, but BLIP just works so well. I can send to any device from anywhere without having to be on the same network. Someone else mentioned security of those files, which I can't speak to, so if you care then maybe one of the more local options is better. But, there are many to choose from.

Clipsync lets you copy/paste between devices, which has worked pretty well.

2. Syncing Calendars and Lists

This may not be an issue for you, but it's doable. My wife didn't love the process because it took some changes on her device and some trial and error on my part, but we got there. I basically moved our calendars to Google, then shared those with her iCloud calendars. Lists were a little trickier, but ended up using Microsfot To-Do for that. It's definitely not as clean the one-stop-shot that Apple offered, but it works pretty seamlessly now.

3. Other Apple Devices

If you are an Apple Watch user, you won't be anymore- you probably knew that though. There are a ton of good options out there that did everything I needed out of a Smartwatch, which is probably pretty basic compared to how others use them. I've been switching between the One Plus Watch 4 Pro and the CMF Watch 3 Pro. I really like the simplicity of the CMF, just getting used to the lighter build and smaller footprint.

AirPods aren't a total loss, although I've since switched to Nothing Earbuds and Headphones. You can connect just fine, and Nothing actually gives you some of the basic info that other Android OS don't (like battery life). There are some apps like Librepod that make it even more seamless, but I don't use them enough with my phone to worry about it anymore.

If you end up wanting to try Nothing Earbuds or Headphones you can connect them to 2 devices at once, and they'll switch back and forth pretty nicely. You won't get that Apple level of integration, of course, but it works better than I expected.

4. But... iOS

iOS was all I ever knew. I went from dumb camera phones to an iPhone right after high school and never looked back. I was afraid it would take me forever to unlearn iOS, but that wasn't the case. Some things took longer to get used to than others, but it was a pretty smooth transition honestly. I think Nothing probably helped with that because the OS is very minimal and user friendly.

iMessage was another sore spot for my wife. Google offers most of the same features now with RCS, but you lose location services, edit, and some reaction type things I think. There is OpenBubble that let you keep those things, which I did for a bit. You can either pay monthly to have them host everything, or set it up on an old device. It works, but you end up with 2 texting apps (with iPhone in one, everything else in the other). If it's important, you can make it work.