The FLE prefix in the macOS shell is a legacy of the flutter-desktop-embedding implementation. Everything that could be shared identically with iOS was eliminated in favor of sharing the Flutter version with iOS, but some of the high-level classes are still completely forked. For each FLE class we need to evaluate whether we can merge with iOS using some availability annotations and/or #ifdefs (FLEPluginRegistrar, for instance, probably falls into that category), or should remain completely separate.

Either way, their APIs should be stabilized as much as possible, and the prefix converted to Flutter. (It's fine if the APIs are incomplete, but it would be good to have reasonable confidence that the APIs that are there are the right ones to keep, to avoid churn for clients.)

This work can be done incrementally, class by class, and some should be relatively straightforward and thus potentially good candidates for someone interested in making small contributions to the macOS shell.