Company Intranet

Based on your requirements, it sounds like you need to find a way to manage multiple SharePoint sites with unique branding and content from a single location. Here are some suggestions:

1. Create a Site Collection: One approach is to create a site collection for each company. Each site collection can have its own branding and can be managed independently. You can set up a global navigation menu that links to each site collection, making it easy for users to navigate between them. This approach can be managed from a single location, but requires separate administration for each site collection.

2. Use SharePoint Hub Sites: While you mentioned that you are unable to use Hub Sites due to unique branding requirements, it's worth noting that Hub Sites do offer the ability to manage multiple sites from a single location. You can apply a custom theme to each Hub Site to provide unique branding for each company. However, this approach may not meet your specific branding requirements.

3. Use Content Types and Site Columns: You can use Content Types and Site Columns to standardize the metadata and structure of your content across multiple sites. This allows you to manage content from a single location and ensures consistency across all sites. This approach does not provide unique branding for each company, but it can help streamline content management.

4. Use PowerShell or PnP PowerShell: PowerShell or PnP PowerShell can be used to automate the deployment of updates across multiple sites. This approach allows you to update all sites with a single script, which can save time and reduce errors. However, it requires a certain level of technical expertise to implement.

5. Use Microsoft Teams and SharePoint Online: You can create separate teams for each company and connect them to their respective SharePoint sites. This approach provides a unified interface for content and communication management, but it may require additional licensing and training for your users.

Ultimately, the approach you choose will depend on your specific requirements and constraints. I recommend evaluating each option to determine which approach best meets your needs.