Chrome already uses plenty of non-native components. Firefox is similar. Moreover while I can understand the concern about poorly implemented components from random web developers, Google is probably the best positioned to implement a widget that faithfully replicates the native equivalent, at least on Android.
> Chrome already uses plenty of non-native components. Firefox is similar.
This is then won't be consistent with native OS apps, but still be consistent across websites. Better than everybody doing different div+JavaScript magic which behaves slightly different across different websites.
you're misunderstanding, this will leave the appearance of the select on mobile up to the web developer