Looking for a plugin/addon/theme/config recommendation for a friend who is migrating from Chrome and prefers the tab UI from there, specifically when there are way too many tabs open.

Specifically, when you open a reasonable number of tabs in any browser, the tabs look like this. However, as my friend has just imported all of his tabs and bookmarks over from Chrome to Firefox, he has an immense number of tabs open right now; in Chrome, he can see all the tabs at once with its UI. On Firefox, however, it keeps things actually legible by not squashing the tabs so obscenely.

"Okay, so I need some help. I've noticed Firefox doesn't show all tabs like Chrome does. Instead it shows a few, and makes me press a button to see more. Please, tell me there's a way to fix that."

I pointed out that this was an accessibility thing (being able to actually see and read the tabs is a useful feature) and they said it was "not good enough". Further explanation of basic things such as using their scroll wheel to scroll through their tabs, or double/triple clicking on the left/right arrows to jump by page or start/end, or using the Ctrl+# shortcuts, are all tools at their arsenal, but that also was not good enough. Personally I'm a 1,000-2,000 tabs kinda person and manage just fine with those instead of having each tab be literally a pixel wide, so I've never looked for an addon to crush all the tabs together like Chrome does, and my attempts at searching the extensions and themes has come up with nothing.

Is there something like this in the about:config page perhaps, or a convenient theme/extension/addon/plugin/etc that my friend can install to feel comfy using Firefox again?