Not all Ukrainians are fluent in spoken Ukrainian. People in eastern Ukraine can understand, read and possibly write in Ukrainian. Just because they were exposed to Ukrainian language and know Russian language which is a similar Ukrainian language. But they are not fluent in spoken Ukrainian. For example, I am a Belarusian; I can read and write in Ukrainian. You can test me. But I cannot speak it well because I don’t speak it everyday. That’s the situation with half of Ukrainians. So Ukrainian is 2nd most ‘spoken‘ Slavic language is not an accurate descrption of a linguistic situation in Ukraine.
In many Russian dialects ‘voiced glottal fricative’ exists. Such as dialects of southern Russia or western Russia. Russians are no strangers to this sound. But yes, they don’t like the sound of it.