Almost all businesses need email, contacts, calendars, live chat, video calls, docs, sheets, and presentations. Ideally all linked. Where is the open source foundation for this package that everyone needs?

Where are the businesses setting up and donating to an organization/foundation to pay for development of such a package?

Aside from email I think nextcloud (+ jitsi integration) covers most, if not all, of those requirements.

Nextcloud is great !

Nextcloud is not great, it's just the only available package that approximates an all-in-one GSuite experience. In practice, the UI is really janky and unpolished.