In a Blazor Web App (Unified), can the Server project access EF Core directly, or is a separate Web API required?

I'm confused about the recommended architecture for Blazor Web App (Unified).

Blazor is often introduced as a frontend framework, similar to Angular or React, which usually means the frontend talks to a separate backend API. Because of that, I'm unsure whether I should treat Blazor the same way.

In a Blazor Web App (Unified) targeting .NET 8, the application can render components both on the server and in WebAssembly. I want to understand the technical constraints of this model:

1. Is it technically supported for the server project to access the database directly using EF Core (without a separate Web API)?

2. In which scenarios is a separate Web API required (e.g., WebAssembly-only components, external clients, deployment boundaries)?

3. How does this differ from the older Blazor Server and Blazor WASM hosted models?

I am not asking which approach is "better", but which architectures are supported and what trade-offs exist in the unified model.

Most examples I find are either old Blazor Server or Blazor WASM hosted setups, so I'm not sure what applies to the new unified model.