Query: Seamless integration & Extended screen

Did you verify that "Safari" is checked in iCloud on the MacBook Air? I don't think the iOS version miss-match with Big Sur is an issue as the technology wasn't introduced with ios 13 or Big Sur.

Paul

Zhubham, the short any sort of.

You can't extend your screen natively anymore "Target Display Mode" is not supported anymore. There are 3rd Party apps that will allow you to extend your screen to either your 2020 iMac or your MacBook Air. I use Duet Display. There is also LunaDisplay.

1. Handoff is what you are referring to for Safari Tabs. It doesn't actually mimic each Safari, Yes it is a setting you can turn on. I use it with my iphone and ipad. When I go to add another tab on my iphone you I can see the tabs open on my ipad and choose from one of those. I have the setting turned off on my mac. So not exactly the way you described but similar function. To turn it on go to system preferences and iCloud and enable Safari.
2. Yes, you can do this as well. This is also in iCloud. Go to icloud drive item and click on "Options..." button and enable "Desktop and Documents folders" option. This will copy your desktop and documents folders to iCloud.

If you have more questions let me know.

I hope this helps.

Paul

Both DuetDisplay and LunaDisplay are not available on the Mac App Store. I've linked to their respective website.

The image below is from my iPhone. to get to the list of open tabs, I press on the icon on the bottom right of the screen in Safari. So on your phone, I would assume you will see something similar with your MacBook Air's name above the list. For the iCloud Drive options. Go to your system preferences. click on the Apple ID icon to bring up a screen where you can turn on/off items that use iCloud. The first item I have is iCloud drive. That is where I was referring. Let me know if this helps.

Zhubham, I should have also asked is it enabled on all devices you are trying to sync Safari tabs? One other point, the list from my screenshot is the tabs that currently open. If you don't have any open then there won't be anything on the list.

Paul