Hey @Muhammad_Luqman 
- just following up as I was able to get some confirmation on this. At the moment, we don’t support injecting scripts into checkout extensibility features, but we do have a method for creating a post-purchase survey extension if you did want to look at that as an option: Add a survey to Thank you and Order status pages
I don’t know how well this will integrate with the current Hotjar script, however this would be the supported method going forward at the moment.
If you did need to migrate from Hotjar, there are some additional post-purchase survey apps available here if you’d like to take a look at those as an option.
I definitely understand this isn’t the most ideal, but I hope this helps a little bit at lerast 