One thing I've come to like about Firefox on Windows that can't seem to be done on Linux

The preview of open tabs at the taskbar in Windows…

Is there an extension or Linux tweak that can do the same (at bottom panel)?

Other than that, not too many things make Firefox a deal for me anymore.

What desktop environment are you using? On KDE Plasma, it shows a small preview of the window on the “taskbar” when you hover over the icon.

Yeah, that depends on what compositor you are using.

The Plasma compositor can do it at least.

KDE Neon.

Only one tab preview at a time appears, whereas all open tabs appear in Windows 10

Vanilla Ubuntu can do that, albeit its a bit buried

Using the mouse a lot makes it handy.

Config of open tabs to scroll with middle mouse just adds that little extra helpfulness.