Just as a side note -- if the user is ok with (or actually prefers) handling the archival & indexing of the material himself/herself, SingleFile works great as a 'read later' tool. It can save into a WebDAV share; can be imported into a self-baked minimal webextension as a library; & has an almost feature-complete mv3 port.
Works on Fennec (based on FFox Beta, I think) though a bit slow, unfortunately. Available otherwise on desktop FFox & Chromium.