SCHIZO THEORY INCOMING:
She's chosen as a streamer to use the Kangaroo Mouse to symbolize her new endeavor. Now, she can be a little bit indecisive with how she wants to brand herself (this is pretty consistent with how she's always been) but it's interesting that she chose that animal specifically, because the Muad'dib of Dune's most obvious influence is the kangaroo mouse. It is possible that she chose the kangaroo mouse specifically to represent her taking on a muad'dib like role, i.e. leading people through the desert.
People more familiar with Dune lore, feel free to correct me. But I get the feeling she doesn't really want to conform to typical twitch-ness due to this decision.
FURTHER THEORY:
Muad'dib is the symbol of the Lisan Al'Gaib in Dune, i.e. THE LITERAL MESSIAH. Ame is positing herself as the VTuber messiah.