Implement OAuth 2.0 based authentication on the Blazor Server Side

I have a .NET 8.0 Blazor web app:

- BlazorApp.Client- Blazor.Server- BlazorApp.Shared

The app uses JWT-based auth between client and server. I need to use an external third-party API to fetch some data which needs OAuth 2.0-based authentication. The code to fetch this data is in the Blazor.Server app.

0Auth 2.0 authorization_code flow of third-party API:

• Redirect the user to the external site using the generated auth login URL.
• Get the authorization_code in return.
• Send the authorization_code to another endpoint and exchange it for an access_token and refresh_token.

Then, add this access token to the Bearer <access_token> to every API call towards the third-party's endpoints in the Blazor.Server app. I am using an auth handler:

public class ThirdPartyApiAuthHandler : DelegatingHandler{        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)    {        try        {            var accessToken = @"// harcoded access token //";            if (string.IsNullOrEmpty(accessToken))            {                throw new UnauthorizedAccessException("User not authenticated with eBay.");            }            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);            return await base.SendAsync(request, cancellationToken);        }        catch (Exception ex)        {            throw new InvalidOperationException($"Error in Authentication Handler while sending request to {request.RequestUri}", ex);        }    }}

I am a bit confused about implementing the OAuth flow in the above handler. How can I redirect the user to the external API's authentication URL in the handler? Is it right to handle this in the auth handler?