Right now you cannot even set up a new Watch device without an iPhone.
The only thing I'd miss dropping to a watch + decent point-n-shoot instead of an iPhone is live photos, which are maybe the most important feature to me from the iOS ecosystem released in the last, oh, decade. Only reason I'd even hesitate to go watch-only.
Right now the Apple Watch is the only thing keeping me from switching away from the iPhone.
If I could pair an Apple Watch with the Razer Phone 2, I would be so happy and never look back. And the problem will only get worse the next 5 years as folding screens come out for the very high end market.
I switched from an Apple watch to various non-Apple smartwatches when I switched to an Android phone. I used a Ticwatch E (for over a year), the new Samsung Galaxy watch (for a week), and the very new Fossil Gen 5 watch for the last month.
The Ticwatch E uses Wear OS, but is relatively slow and has battery life issues if you are not careful; however, it is very light (40 grams with band!).
I tried very hard to like the bigger Samsung Galaxy watch, but for me it was far too heavy (63 grams + band), which drove me nuts, and the app ecosystem was painful to me. In fairness, the battery life was really amazing though.
I currently wear a Gen 5 Fossil, which weighs 45 grams + band, and is fast enough, with a lot more RAM/storage than the ticwatch and newer generation processor. I'm happy with it. (For comparison, the Apple Watch case is 50 grams.)
Overall, I like Wear OS significantly more than the Samsung watch operating system (which I really didn't like, due to the apps being so expensive and limited). Wear OS is also nice because there are tens of thousands of watch faces to choose from, and some of the faces (that cost $1) are also very highly customizable.
The Apple Watch Series 5 is an absolutely incredible piece of technology, and I wish I at least had the option to choose it, but I guess I don't since I'm not using an iPhone...
This is the latest one.