Location
The location of the average visitor to my site will probably be inside the United States, as I'm primarily intending it to be something to share with my friends and family. However, I could also share the link on social media and sites like Letterboxd, where I have followers that live in other countries around the world. It will probably be best to make sure the site is one that can be accessed internationally.
Age
If I had to pin down an age of those who would visit this site, it would probably be peers of mine near my age, so mostly people in their 20s.
Gender
I would say more than half of the friends I have in life and online who share my interest in movies and physical media are identify as male. I wouldn't say the vast majority are male, but like I said, probably at least half.
Other
Other demographics of visitors to my site might be people I know irl versus people I know online, as well as family versus friends.