Translates to "would like anyone" or "I love anyone." This is an idol/wota term that denotes a person being a fan who can like anyone in a certain group, as opposed to only one person. In the VTuber landscape, a daredemo daisuki is someone who may have one or two favorite VTubers but is completely open to and may regularly watch others as opposed to sticking to exclusively one or two. Can be abbreviated as "DD."
▸ "Hard for me to make time for anything since I'm kind of a daredemo daisuki."
▸ "Daredemo daisukis are insane, especially those that can watch multiple streams at once."
▸ "I love VTubers and VTuber culture as a whole, and that probably explains why I'm a daredemo daisuki."