GP comment mentions that userspace apps on Fuschia are predominantly Flutter apps, which isn't only running Dart (in a VM), but also using Skia for 2D (and 3D?) graphics, and that isn't going to go faster than native. With Fuschia, I believe the primary objective has always been a secure kernel base to build the rest of the OS upon. That is pretty hard to do with Linux without performance costs or support from underlying architectures (ex: https://github.com/google/kernel-sanitizers).
The Android Runtime otoh has long moved to AOT for hot-paths (profile-guided optimization) and JIT for the cold ones.
The biggest difference is that while some Android devices might be a sluggish if too many applications are taking liberties with memory, on iOS they just die, specially on Objective-C code, where not everyone checks all pointer related code.
There are still a lot of midrange phones out there, and IOS has always felt smoother.