Funtoo Linux has an ebuild forking article for new contributors that wish to get new software into Funtoo Linux. However this article was last edited in 20 feb 2019.

https://www.funtoo.org/Forking_An_Ebuild

Funtoo has long moved from the Gentoo ways in terms of packaging in both ebuild and autogen format. This article should be reviewed and mark what is obsolete and what is not in terms of new funtoo packaging. 

I'll take responsibility for adding examples as well as screenshots to further explain this process in the classic ebuild side of things.