The WavePlayer author here. I am already preparing an update to my WordPress plugin that will make it fully functional as a Gutenberg Block. The first tests are proving very rewarding but Gutenberg is still at an early stage of development to think a possible porting of our asset to the new editor.
This prevents my plugin from working until they fix the Gutenberg plugin on their end. Specifically, I have just sent a pull request to the Gutenberg project on GitHub asking for a change in the code of the MediaPlaceholder component that is currently forcing the MediaUpload component to be an image gallery when multiple files are needed, regardless of the type of media requested (audio files).
I don’t see how this is going to happen within the final date of this contest, which is in four days.
Since WavePlayer is a plugin offering audio playlists with waveform display, it would be impossible or very convoluted to make it work until they change the Gutenberg plugin code on their end. After all, Gutenberg is still missing an official block for audio playlists, even for the one offered by WordPress in their core components.
In addition to all that, the “loads of resources out there” that you mentioned in your OP are quite often not working or contradicting, just because things are drastically changing at a very fast pace there. Even some resources from the official documentation were not updated to the latest changes in the build or contradict what the code is all about, as I pointed out in this issue report.
For the reasons above, it is quite premature to have this contest now, because our hands are tied by the early stage of development currently going on at Gutenberg. There are currently more than 1000 issues reported and more than 200 pull requests.