GetAccessToken_DefaultAzureCredential.cs

using Azure.Identity;

public async Task<string> GetAccessTokenAsync(string resourceUrl)
{
    var credential = new DefaultAzureCredential(); // Or new ManagedIdentityCredential();

    var accessToken = await credential.GetTokenAsync(new TokenRequestContext(scopes: [resourceUrl + "/.default"]) { });

    return accessToken.Token;
}