There's also a locked door in one of the buildings, but I couldn't figure out what either mean if anything. It would be cool if the radio was used for something though

The radio in the treehouse might be relevant. See my sibling comment.

https://news.ycombinator.com/item?id=47961275

Yeah I saw that too, but the list of all accessible rooms is also in the code and the only scenes I see are

  default
  sauna
  tent
  cave
  treehouse
  house-main
  house-cafeteria
  house-bedroom
  house-trophey
  boat
  telescope
It would be really cool if there were some secrets, but alas it appears not (unless it's obfuscated in the source as well)