I was wondering if there's a direct URL to a Item so I can link to the item IN business Central from our own backoffice system.

I was wondering if there's a direct URL to a Item so I can link to the item IN business Central from our own backoffice system.
Yes you can filer by url. This is the url for your case:
businesscentral.dynamics.com/ IS '10000'
This opens the item with No. = 10000 in the company called CRONUS International Ltd.