1) is that feasible to customize the modern pages page layout? as we do in classic attach a content type and we have to fill the required metadata before publishing that page.
2) Can we add an app from SharePoint app store in modern pages?
View best response
when can we expect Microsoft to provide the ability mentioned i bullet no 1?
As said by Juan Carlos González Martín it was announced in a roadmap but for now there is not date of release.
For advance modification you have to use publishing site but forget new design,
Wait & see !
I believe you can add apps on modern pages but you have use SharePoint Framework to develop apps and deploy on the apps catalog