What other SharePoint integrations besides Power BI and Access would you like to see in Business center?
One more comment. I think many of the suggestions here could be easily handled if Business Center was integrated with SharePoint or was a site (template).
As you know SharePoint offers a great team environment. Small business, which seem to be the Business Center targets, need to operate efficiently as a team because of resource limitations. SharePoint List, Document Libraries, Tasks etc. are great tools for this. I think it would be great to have Business Center as a SharePoint site so you can have Customers, Project, Employee information integrated with Business Center. See my blog https://sp4smallbiz.com/ for further ideas on how the integration would help small businesses.