I'm curious -- Roam Research appears to have won over a lot of folks with this kind of need recently. You didn't list Roam among the prior art -- do you think it's not really relevant? I can certainly see Roam eventually including cross-platform bookmarking/archiving, etc.
By the way, I think you should also take a look at Archive Box, which is very much in this direction: https://archivebox.io/