hey @leostelas !
looking at the site, it seems that on project pages like these:
https://www.franzgruenewald.com/projects/greek-island-hopping
when you scroll to the bottom, you simply have the selected projects again, which in lay theme's case would be for example a thumbnailgrid element:

you could create a page to use as a footer.
this footer should contain your "selected projects" thumbnailgrid.
then in lay options -> footer,

just set that page as the footer for projects.
this way at the end of every project, you would have the overview of all projects!
in lay options, you even have this setting that can be helpful for this kind of footer:
















