Gepenyan, At this point no. But, this is a really good enhancement request! Thanks for asking.
I have added a GitHub issue to track this: github.com/atapas/notifyme/issues/5
A bit of background to this:
I am using the Bell icon from feather js.
import { Bell } from 'react-feather';
As part of the enhancement, I will have to keep it open for an icon supplied as an optional prop.
Btw.. feel free to do any changes to the code. I may get to it a bit late. Repo is here,