Need help adding meta fields to an existing admin menu

I want to add some meta boxes under “Settings >> Reading >> Front page displays” in a small plugin which will be part of a much larger “group of plugins” (sort of a framework) that I’m working on where there will basically be a check-box and when the check box is selected, it adds a drop-down menu just like the other drop-downs in the “static page” options. This is for the selection of a splash page for users who are not logged in. Logged-in users will see the normal “front page” but people who are not will be directed to that “extra” page.

I want to either add it to “Front page displays” or make a separate row right above or below “Front page displays” that is called “Splash Page” or similar.

I’m also not incredibly talented with meta boxes, so a little advice (or links/tutorials) related to how I can make them actually save the data correctly would be appreciated too.

If anyone has any insight or advice into how I might accomplish this, it’d be greatly appreciated. Thanks for your time!