Hi, I do plan on updating but will be quite a while before the next update. Currently there isn't any art to unlock.
There are 18 Streamers. Hope this helps.
1Squink
2 Venus
3 Ranchu
4 Marshal Marshal
5 Marigold
6 Astrid
7 Lily
8 Deja Brew
9 Mykok
10 Jeseed
11 Snu
12 SuuYuu
13 Blitz
14 Soara
15 Yondle
16 Abyssa
17 Pheffer
18 Sleek