Flutter has big advantage in this area as it doesn't wrap OS's controls, but has build it's own controls on top of lower level OS's APIs.
Avalonia (which also renders it's own controls) has posted an article, describing how it's easier supporting new platforms this way: https://dev.to/avalonia/avalonia-platform-support-why-its-si...
Avalonia GUI apps can run on Linux without a desktop environment installed because of this.
Either way thanks for the link, I’ll check it out.
However, framework developers often develop controls that emulate platform controls. Not all are 100% match. Depends on the quality of the implementation.
The quality of Flutter controls is not yet on par with iOS's controls, but if they continue to improve at the same rate as they currently do, in 1-3 years they could match or even surpass them.
edit: silly mistake Android is open source, not sure how much it helps when compatibility layer is not a priority for the OS developers