That looks interesting!

Does it also have a way to deal with sets of "related" links? For example I might want to save and archive a webpage and its discussion on HN together or a collection of multiple blog posts as single entity. Currently I use org-mode but, even with org-capture, it is not frictionless and the mobile integration is lacking.

I’m afraid not. But this is an interesting idea.

Looks great. The front page doesn't mention which browsers it integrates with: is it Safari only, or does it plug into Firefox and Chrome too?

But it's a subscription!

Bookmarks are data. I don't want to have my bookmarks under the control of something that will lose them or make them inaccessible any time.

It has browser extensions for Firefox, Chrome and Edge. Not just Safari.

Anybox has lifetime option. It stores data on CloudKit and has many ways to export your data. I will never take user data hostage.