I have a custom implementation of .AddOAuth() in .Net-Core.  I've created a nuget package for Authentication using Coinbase (which is basically a clone of the add google implementation plus a few custom options specific to coinbase) full source.   I've looked at a few other questions on this however they don't seem to implement OAuth (e.g I cannot pass scopes) I would like to login using OAuth But I want to return to my clients a JWT.   
When I try to use JWT with AddCoinbase ( which is just a derrivative of AddOAuth)
services.AddAuthentication(JWT_BEARER_AUTH)
.AddJwtBearer(cfg =>
{
    cfg.RequireHttpsMetadata = false;
    cfg.SaveToken = true;
    cfg.TokenValidationParameters = new TokenValidationParameters()
    {
        ValidIssuer = Configuration["Tokens:Issuer"],
        ValidAudience = Configuration["Tokens:Issuer"],
        //TODO: get key from secret section
        IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Configuration["Tokens:Key"]))
     };
 })
 .AddCoinbase(options => {
     options.AccessAllAccounts = true;
     options.SendLimitAmount = 1;
     options.SendLimitCurrency = "USD";
     options.SendLimitPeriod = SendLimitPeriod.day;
     options.ClientId = Configuration["Coinbase:ClientId"];
     options.ClientSecret = Configuration["Coinbase:ClientSecret"];
     COINBASE_SCOPES.ForEach(scope => options.Scope.Add(scope));
     options.SaveTokens = true;
     options.ClaimActions.MapJsonKey("urn:coinbase:avatar", "avatar_url");
 });
After I login to coinbase the external callback redirects me
[HttpGet("ExternalLoginCallback")]
[AllowAnonymous]
public async Task<IActionResult> ExternalLoginCallback(string returnUrl = null, string remoteError = null)
{
    if (remoteError != null)
    {
        //TODO: Handle remote error failure
        throw new Exception($"Error from external provider: {remoteError}");            
    }
    var info = await _signInManager.GetExternalLoginInfoAsync();
    if (info == null)
    {
        //TODO: Handle null external login info
        throw new Exception("Error: could not find user info");
    }
    // Sign in the user with this external login provider if the user already has a login.
    var result = await _signInManager.ExternalLoginSignInAsync(info.LoginProvider, info.ProviderKey, isPersistent: false, bypassTwoFactor: true);1
    var user = await (result.Succeeded ?
            _userManager.FindByLoginAsync(info.LoginProvider, info.ProviderKey)
        : this.CreateIdentityUser(info));
     await _signInManager.UpdateExternalAuthenticationTokensAsync(info);
    _logger.LogInformation("User logged in with {Name} provider.", info.LoginProvider);
    return Redirect(returnUrl);
}
After the redirect I never receive a JSON Web Token I always receive a Cookie. How can I leverage OAuth Authentication while serving JWT to my Clients?