Gonna unpack these in small groups. I'll start with things I believe the client already does or will do soon.

when I click a band tile, the “Albums” icon is too small. Ideally have album tiles horizontal along the bottom, but at least make the icon bigger and put next to Instant Mix

If the artist has albums, you should be able to press down on the remote to get to the album section without having to use the left icon menu. That menu is really only there to help people like me who have some artists with dozens of albums and I don't want to have to press up through all of them to get back to the top. It's a little jump menu.

Instant Mix is confusing, it seems to be shuffle just name it shuffle, and if you hit shuffle from a band details I’d expect it to shuffle just that band, vs “Shuffle All” from main screen, or Shuffle album from album details, etc.

Instant mix is kinda like a radio play option. It generates a playlist based on the band you're on. To play all the songs by the selected band, press the Play button on their artist page. To shuffle play the artist, currently you can press the play button on their artist page then enable shuffle mode.

The upcoming 2.0 release will provide a new option where you can simply press the play button on your remote and it will shuffle play all the songs by the currently highlighted artist.

The rest is probably just me needing to get used to the playback button design, like pushing up I’d expect to see progress bar and some quick functions but instead I see file info which doesn’t seem like a common thing I’d care to look at. Similarly, being able to click the progress bar and skip to a time would be wonderful vs hitting “right” a hundred times on my crappy Roku remote.

The upcoming 2.0 release replaces the playback info and subtitle select popups with an OSD (on screen display). It has buttons to play/pause, skip by chapters, a chapter list, and the moved playback info and subtitle select popups. It also shows you where you are in playback (but this bar is not selectable due to technical reasons - thanks Roku 👎