I have a hosted Blazor WebAssembly App and I tried to scaffold identity server in the project App.Server. It's working but now I have a mix of cshtml view files in the App.Server (which was intended to be only a asp net core web api). I found hard to integrate the Blazor UI and cshtml files to have a nice user experience.
I was expecting to have a separate pure web api with identityserver api and Blazor taking care of the pages/views and api calls. Is it possible to move those cshtml to Blazor and manage the pages from there or the scaffolding has been done that way because is not?
No, you can't move those Razor Pages pages to your front-end Blazor. But you can design them in such a way as to create the impression that, when the user, for instance, is redirected to the Login page, the Login Razor Pages page is part of the Blazor front-end. I've seen an example of that, and must admit that I couldn't discern it without seeing the source code.
Having a dedicated Web Api project or having Web Api end points in your Blazor server project has nothing to do with the Identity UI not being part of the Blazor front-end.
I was expecting to have a separate pure web api with identityserver api and Blazor taking care of the pages/views and api calls.
You can create a Blazor WebAssembly stand alone project, add a Web Api project, and an IdentityServer4 project, in which case, the flow of OpenID Connect is such that your users wanting to log in are redirected to the Login page provided by the default template of the project, but you can still design the pages to look as though they are part of the Blazor front-end.
The only viable solution that can satisfy your whims is to use Bearer Authentication; that is your Web Api produces Jwt token for users, which are passed to your front-end, and stored in the local or session storage. In that case, your Login page can be a Razor component that gather credentials from the user, and pass them to the Web Api appropriate end points via the Fecth API (this is the HttpClient service in Blazor)... This was the method we adopted before the Blazor team have created the current authentication system of Blazor. Personally I wouldn't recommend one to do that unless he is proficient in Blazor and other fields, and he's ready to invest a great deal of time for developing it. I guess your solution should be deception: let the user think that he's never left the space of the Blazor SPA...