I can second both the availability and quality issues. Tried to get a Kotlin dev for Android via Toptal and settled for Java when they said they basically had 0 Kotlin experience on staff.
As for quality, the app worked and works well, but there were some serious WTF design decisions made that have made it impossible to maintain the app, not to mention total lack of testing.
I think this has always been the case no matter what language is used. Body shops push crap, it is just the way of life. It can be crap java, javascript or kotlin the fundamental of why they are shoving crap is not going to change because of the implementation language.
As for quality, the app worked and works well, but there were some serious WTF design decisions made that have made it impossible to maintain the app, not to mention total lack of testing.