Design navigation

Here is another thought. The very long list of vendors is clearly not a great user experience. And it will get more complicated as you add more vendors. As a general best practice, you want to keep the total number of links in your navigation to fewer than 100 (for performance reasons) and 499 (capacity). But even 100 links can be difficult to manage. One option to consider is to have a link that goes to a page where you can display all the vendors and links. The other is to have navigation links to your top or "featured" vendors (10-15) and then have a link to a page that lists all vendors and allows the reader to sort and filter by name or characteristic. Here is a link to some guidance on the Microsoft Learn site: https://learn.microsoft.com/en-us/sharepoint/plan-navigation-modern-experience. (In the spirit of full disclosure, I wrote the guidance.) I would encourage you to think about not just if you can do what you are trying to do but also whether it is a good idea or if there might be alternative approaches to get the same outcome.