It's a really far stretch, but I get the feeling this guy from a picture in an IO hideout in BR might end up being Dr. Vinderman and STW might be another simulation / pocket reality controlled by IO too. Chiseled jaw, small eyebrows, and the hologram has a bit of hair hanging which could be the silver highlight in his hair.
Sure, the hair is different but the hologram was made whilst Dr. Vinderman was in distress about the storm in the STW story, maybe to be more convincing for the characters of STW? Dennis could also be heard in the "Foreshadowing" quests last season in BR and there was special NPC dialogue in Battle Royale between Power Chord and Penny, and Kyle and Ray in Chapter 2 Season 5 if I remember correctly?
Perhaps the two realities are merging?
My second theory is that the STW universe is the "Real World" in Fortnite, not a simulation / pocket reality, also that Dr. Vinderman faked his death, and that there's actually other parts of the world that are completely fine as he left the area we know in STW in the dust.
In the STW questline "School of Hard Knox" Knox mentions that he used to be a "Database Administrator" and that the "Agency" who hired him asked him if he could "keep his mouth shut" implying there was secret stuff happening, just like IO has alot of secrets they try to hide.
Something that seems to disprove this is that Knox says that it's no longer around because everyone was gone because of the storm, but I feel like that was a lie from Knox to hide intel, as he constantly lies to Lars in this STW questline and dodges questions about the topic. The storm also has something to do with IO in BR, maybe it does in STW too, if they do exist in STW?
I think Knox's constant question dodging, added with the possible leads might mean that IO is in STW and that Dr. Vinderman isn't dead. What do you guys think about these theories?