I've been able to get surprisingly good animation performance on an NBU quality device as well with Houdini's Paint Worklet.
You do have to be intentional to get good animation performance on the web, but it's amazing that when you are, you can make transitions that perform better than the ones that come with the phone.
Absolutely - I've seen native apps struggle to provide the same animation performance as our PWA. It is hard work though, and I've seen even the best web devs fall short on performance. We luckily hired an absolute gem of a developer that thoroughly understood JS and CSS animations. We make sure we retain her, because her work makes our PWA infinitely more usable.
You do have to be intentional to get good animation performance on the web, but it's amazing that when you are, you can make transitions that perform better than the ones that come with the phone.