- Edited
Niko I find tab nesting/indentation in Orion much more useful than pinning and folders in Arc. Also, suggested "Tab Groups" will essentially give you folders. And, as a cherry on top, you'd still have your bookmarks in the panel, which could be managed separately. It could help to declutter sidebar, but still keep everything at hand. I feel like it could be the best of both worlds, but, of course, I have no data to back that up.
When you say "bookmarks in the horizontal tab bar", you already have them (⌘+⇧+B). So, basically, I think that trying to clone Arc's features and terminology into Orion would just create unnecessary confusion. It's a specific mental model, that resonates with a narrow user group, and that whole browser is designed around it.
When I say "terminology", even just using words in the discussion that you linked creates confusion, not to mention mockups. Imagine how it would look like in production then. Here's what I mean:
Arc | Orion |
---|---|
Daily Tabs | Open Tabs |
Favorites | Pinned Tabs |
Pinned Tabs | - |
- | Bookmarks |
On top of that, Orion even has "Favorites" too, in the "Bookmarks" panel.
Another thing regarding the discussion you linked, somebody was talking about differentiating two pinned tabs from the same website (e.g. Google Docs), but he was essentially talking about renaming tabs, not pinning them. That's another topic.
TLDR;
I don't think that mix & match of tabs and bookmarks would work and feel intuitive in Orion.