Why not use your window manager / compositor for this feature?
Firefox
A place to discuss the news and latest developments on the open-source browser Firefox
For one thing, you don't have to struggle with a shrunken top toolbar.
There's a good reason a significant and increasing number of browsers (including Floorp, a Firefox fork) and other applications include view-splitting within them.
There's a reason Mozilla made Side View for Firefox.
I kind of feel this way about tabs, but everyone loves tabs so much I'm often too embarrassed to say anything.
Plasma (KDE) and Windows can both stack lots of windows just fine, so, why not let the window manager handle this and keep the browser more focused on browser tasks?
Wait, so instead of using tabs in your browser you just... put separate windows on top of each other, and use your taskbar/keyboard shortcut to switch between them?
You should use it the way I do and nothing should ever change.
Everyone says "do it with your compositor" but I don't think anyone who says that has ever really tried the convenience of split view.
My biggest problem with simply opening two Firefox tabs is that my tabs split, and sure, I can just drag them around, but for me (TWM user) I prefer to be able to do everything from the keyboard, and moving tabs between windows is not something that can be done do with key shortcuts
My compositor does this for me. Not Firefox.
Yeah literally anyone can do that on any OS. But it’s a lot clunkier than simply showing tabs side by side in the browser itself
I find the browsers’ various implementations to be far inferior to the built in system split screen. They really overwork my already overstimulated ADHD brain.
Not everybody has a compositor that allows you to un-maximize, minimize, restore, move and resize two windows adjacent to each other simultaneously.
Which one supports this on Windows and Linux?
PowerToys has FancyZones for Windows.
It's a valiant effort to allow functionality for window tiling, but like the name suggests it's for arranging things on a screen. It can't really facilitate two windows behalf as if they're one window split in two.
The truth is there is not a tool out there for every use case that gets posted here. You're going to have to weigh your options and pick what works closest to what you need. In my case, opening a new browser window will make my compositor mimic this behavior to an acceptable degree. Also in my case, it will not work on Windows. This is a trade off I am willing to make. It also might not be the best idea to want a feature bloated browser. How many people will use this over PowerTools/their preferred Linux compositor? Probably not many.
Unrelated to the OP, but your Unraid docker dashboard seems to be more horizontal than vertical, as in the apps are lining up horizontally. Is this something you did yourself? Don't recall that being an option in Unraid. And am now all too curious about how you achieved it 😅