It's a bit hard to say for certain. Comics can sometimes leave such aspects open to interpretation, and it might not be explicitly stated whether Larry Trainor is gay or not.
Since we only know the title 'the real megan is missing story', it's difficult to say exactly who Megan is. She might be a young girl from a small town, or a woman living in a big city. Maybe she has a family, friends, and a job that are all affected by her disappearance.
There's not enough information to know exactly who Megan is in'megan is mossing real story'. It could be a common name for a fictional character in a story that is being developed, or perhaps it's a real person that the speaker is familiar with but hasn't provided enough context for others to identify. For example, it could be a Megan from a school project where a real story was expected but is missing.
I'm not sure if there is a publicly known romantic love story between Daryl Sabara and Meghan Trainor. They may be just friends or colleagues in the entertainment industry.
I'm not sure exactly who Megan is without watching the story in detail. But she's likely a person who has a very high weight and is on a journey to change her life in the context of 'my 600 lb life'.
It's hard to say for sure. It depends on how it was written and presented. Maybe the author drew inspiration from real life but changed some details for the sake of the story.