Just a check box to save that we've read a chapter on a team's own site so I don't get pinged even after I've read the chapter on their site

[JustNatsuki]

For example: Chapter 5 of ___ manga hasn't been released yet on MD but has been on team's own site. give an option to add the eye symbol on that chapter's page or in the main manga screen

 

[Holo]

You will be able to toggle the display of unavailable chapters in all lists on MD very soon, for this exact purpose.