I guess it may have to do with the fact that shannon was in the villa for 2 days so realistically she wouldn't gain as many management deals in comparison to someone who leaves the show further in.
Also. she's been pretty vocal about her disdain about the show so that isn't benefitting her, and most good management deals are less likely to want to sign someone who's bad-mouthing the show.
however, I did watch an interview she did about her experience on love island and she was really articulate and the interview was interesting so maybe she could make a youtube channel and talk about her experience but realistically shannon will probably continue whatever she was doing before love island as she was barely on the show for that long.