you do not need index route for comments. That info can come along in the posts jbuilder.
For connections, experiences and education, you of not need separate index routes, unless you are planning on building a separate show page for each. (show pages for each of these would be bonuses)
You do not have to worry about showing just one post. That can be a bonus.
snake_case
GET likes
api endpoint because that info comes through the post show