index.html or Raw HTML insertion into a page?

I have a site where I would like to either A) temporarily show an index.html in the root with WordPress set up in a /wordpress subfolder (I'm assuming via .htaccess redirection for the root (/) visits) or B) by inserting raw html with direct paths to assets within a WordPress page that is set to the front page of the site.

This is just a "coming soon" page that we've had in place and want to retain its presence until a new site is finished being built, however we do need some of the WP functionality immediately in order to facilitate a few things for other paths of the site.

Which of the two would be the best approach and what's the best way to accomplish either of these, or another route if you have something in mind?