This will be challenging. Insights needs a lead/contact. Now you could flag other members of the account perhaps so if they are working accounts and look into contacts that exist they may see it. Activities really are best when viewed against the individual.
Now, that being said, you could probably develop a campaign that looks at new users and trigger off of account number change from blank to something then insert an Interesting moment if the company was part of the initiative.
Similarly you could have a master campaign that shows participants and then as these orgs get new people you add them to those campaigns.
If you knew the account names, then you could send an alert or email to the Account Owner. Just setup a smart list and an email to go out via Send Alert > Account Owner.
Of course if you had different Account Owners and Contact Owners, it would be harder to be accurate.