I'm planning to create 1 HR communication site with 4 document libraries (IT, Legal, Marketing, Sales), and 4 pages (IT, Legal, Marketing, Sales). Each page will contain the respective document library and some articles applicable for that department. The site will have navigation bar taking the user to each page. Only members of the respective department (we have Azure AD groups per department) should be able to access that department's page/documents.
For example: I want to allow only members of IT to view the IT page. Does SharePoint allow me to apply permission at page level? If so, then do I also need to apply the permission at document library level?
Is there a better solution, for example instead of pages do I create 1 site for each department? or maybe 1 sub-site for each department?