There was a recent discussion about bookmark management, so one possibility is that you could use a bookmark manager and simply bookmark all of these things, and it would be “content agnostic”. I think one of the best pieces of software I’ve integrated into my workflows this year is Anybox, which is a bookmark manager. Since everything you mentioned has a URL associated with it, you could conceivably keep all of those in a bookmark manager with some combination of folders, tags, statuses, etc. to keep track of what you want to consume.
For example, I usually keep PDFs in DEVONthink, and for those I want to read, I might add a “to read” tag to the document in DEVONthink. Since Anybox supports URLs from apps as well as websites, I have that tag bookmarked in Anybox, so it’s easy to both mark something “to read” (in DEVONthink) and access those items I’ve tagged “to read” (in Anybox). Anybox has good Shortcuts and Widget support, so it’s easy to both add and access content in that app on various platforms using various workflows/approaches.
On the other hand, you could also use specific apps and services that have appropriate metadata for the content type, like IMDb for movies and TV shows, as you mentioned. I’ll put in a word for LibraryThing for book management. I started adding books in my library, books I wanted to read, books I had read, etc. back in 2008 and have been using it consistently ever since.