Extended attributes are messy. E.g. the equivalent on Windows (ADS, not EA, which also exist separately) can store arbitrary amounts of data, I'd expect resource forks on macOS to be similar. Meanwhile Linux only supports 64 KB of data for them, though most Linux-native file systems have an even lower one block limit. And then there's Solaris where extended attributes are actually an FS namespace.

So even if both file systems support extended attributes, does not mean that you can actually preserve them.