If you’re having trouble with reading without getting distracted, there’s browser extensions that you can schedule to block all the distracting sites at certain times on certain days. This really helps you keep to a certain schedule for being productive, it’s something I would start with (Leech Block NG on firefox is pretty good for example)

As for how to retain it better, I always like to watch lectures and interviews with the authors if they’re alive, or for older works there’s usually discussions or companion lectures like David Harvey’s Reading Marx’s Capital.

E1: Something that helped me particularly was getting a solid grasp on the specific assumptions and methodology of Dialectical Materialism, studying it as if I was learning to do math. Mao’s On Contradiction and Stalin’s Dialectical and Historical Materialism are pretty short works that explain the framework very well, so it should let you cross-reference any difficult idea you find in other texts by trying to build it up from first principles.

E2: Completely tangential, but I recently started playing The Talos Principle 2 and (this might sound completely consumerbrained, I know) it is legitimately a pretty good way of engaging with a lot of different philosophies, but it focuses on Dialectical Materialism and does a good job of explaining how it relates to the others. If you have a decent gaming PC it might help retain some more of the concepts if you played it.