Are Fluent UI Web Components used by radzen at all? Is the Fluent UI Theme all done with CSS? Will Fluent UI continue with Home - Fluent 2 Design System?
No, Radzen Blazor components are not Web Components but native Blazor componets made from scratch - you can check the source code for reference, it's all free and open source with MIT license.
Yes
We don't have plans for that at the moment however we might add it in the future.
Yes, the Fluent UI theme follows the Microsoft Fluent 2 Web as closely as possible. However, there might be subtle differences due to the different implementation of the components and the evolving Fluent 2 design system. You can see that even the Fluent UI Web Components are still not up to date with the latest designs, here is one example: Accordin theme fluent not corrent position expand/collapse · Issue #1668 · radzenhq/radzen-blazor · GitHub