Thank you for the feedback, I've just updated the extension.

You can now set your location via many ways, there are now reminder alarms/countdowns, and you can click on any prayer time to see the remaining time.
I hope you enjoy the update.

Update(x2):
Done, thanks for the useful feedback!

There is also a desktop version of the extension available.
You can download it from "https://github.com/mohamedsameh20/Zakkir"