The season for not opening the Opera browser in Kali is that, opera can’t open with the root account. So you can use the following trick to open opera as an usual application in kali linux by following the simple steps below. (i assumed you have already downloaded and installed opera in kali)
Step1: Goto root (“/”) using the Files (explorer).
Step2: Just type “opera” to search that term, and select the search result with the location “usr/share/applications”.
Step3: Right click on that and select “Properties”. On this window, you can see the Command field as “opera %U”
Step4: Change this field to “opera –no-sandbox %U”
That’s it. Now you can run Opera in kali.