I'm thinking of the common definition of 'opinion'. "Which is better, chocolate or vanilla?"
The question seeks a solution, and the simpler answer to the question is actually what I think I'm going to implement (in comments):
"Add everything and create a commit before your freelancer does anything, then look at the history that happened afterwards to see what changed. [...] if the freelancer goes into the .git folder and tries to mess with the files then it'll be super obvious, any git command will raise alarm bells, every git subcommand does a verification and integrity check."
I'm thinking of making multiple clones on the server, and offering FTP to the cloned directories.
The opinions I read are in the answers suggesting:
"If your freelancer can modify git without git knowing they're in for a nobel prize"
"Shared hosting is not the most useful hosting, aside from it being cheap. "
"...it's hyper localised to your specific case" As the Rapper 50cent says, lots of guys have 50$ bucks