I like the list, I like the box for entering a technology, but you already know what browser and OS I am using. Keep that list and box, perhaps on one side, but show me another pane with some information about potential vulnerabilities on my machine.
Start with what you know - my OS and browser - then have common but unconfirmed SW, e.g., Adode (a good bet), either MS Office or Libre/Open Office (pretty likely I have at least one), Pages, etc. (in my case, eh?). Add a third section to that right-hand pane with some user profiles, e.g., "are you a developer (vulnerabilities in brew? npm?)? an officer worker (typical office stuff)? a designer (advanced Adobe products)?"
You could go a long way with those, without having to scan my machine.
Get some cred, write a scanner, offer that too. I might use it.
(I think it was CNet that used to have a service like that for Windows - I really liked, but they dropped it before I dropped Windows, and that was a long time ago.)
My advise would be - aggregate! There most annoying aspect in security news tracking is wading through multiple iterations/announces about the absolutely same vulnerability. Of course that type of aggregation is much easier said than done :)
The bottom page is somehow broken in the latest Firefox, the paragraph exits from the gray box.
I don't want to register to receive the updates, do you have other ideas about the notifications?
If you like your product, don't give up.