What do widgets/browser extensions have access to?

Question

safari

Interested in the ability to track the behavior of the user who installed the widget / extension for the browser.
What can be tracked?

• search terms
  
• location region / ip-address
  
• reading cookies when visiting websites
  
• site visit history
  
• time spent on websites
  
• input data in the fields name=name/phone/email/company
  

Is it possible? Thank you!

Answer 1

Everything from the list, but I would never put an extension with similar rights (displayed during installation).
Although people usually do not look at them.