This is a feature in Chrome, where it's really easy to do that.

It would be easier for users to create two spaces, where one is for studying and the other browser is for working for example.
If someone has already opened them, but can't drag and drop tabs to another opened instance of Opera GX they have to open those webpages again on a new Opera GX process, and paste in the progress they've made on the other tab.

[Suggestion]
Making it easier to drag and drop a tab to another opened instance of Opera GX