How to use already coded html page as squarespace website

Site URL: https://nlshawver.com

So essentially, I have a pre-made site on my hard drive already, with all the HTML and CSS already coded. It all works on its own, but the question I have is:

Would it be possible to upload or copy+paste that HTML file to my squarespace main index page as the home page of the website? Just to get all the formatting and extra stuff straight from my file instead of having to re-build the entire thing from scratch in the editor.

Thanks in advance, hopefully there's a way to do it :)

I believe developer mode will allow this:

https://support.squarespace.com/hc/en-us/articles/205815928-Adding-custom-HTML-CSS-and-JavaScript

and this might help as well. https://developers.squarespace.com/

If your file has only html/css.

You can create homepage

You can upload css https://support.squarespace.com/hc/en-us/articles/205813928-Uploading-and-managing-files

add Code Block > Paste html > declare link rel to css file

Then use CSS to remove header, footer