API for automating Azure DevOps Pipelines?

Seems I was bad at googling:

Trigger Azure Pipelines build via API and Start a build and passing variables through VSTS Rest API (found via the searching for [azure-pipelines] apihere on StackOverflow) point me to the Azure DevOps Services REST API that I had mentioned above.

I too have been working on automating DevOps pipelines and keep winding up back here. Some of this information appears to be outdated. As of the time of my writing this, I believe this article in the Microsoft Docs is the most recent. I did have to scratch my head a bit to make it work, but wound up with this code

public static async Task InitiatePipeline(CancellationToken cancellationToken = default)
{
    using(HttpClient client = new HttpClient())
    {
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        var token = Convert.ToBase64String(System.Text.ASCIIEncoding.ASCII.GetBytes(string.Format("{0}:{1}", "", AppSettings.DevOpsPAT)));
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", token);

var repoGuid = "Put GUID Here"; // You can get GUID for repo from the URL when you select the rpo of interest under  Repos is Project Settings
var bodyJson = @"{
    ""parameters"": {
        ""parameterName"": ""parameterValue""
    },
    ""variables"": {},
    ""resources"": {
        ""repositories"": {
            ""self"": {
                ""repository"": {
                    ""id"": """ + repoGuid + @""",
                    ""type"": ""azureReposGit""
                },
                ""refName"": ""refs/heads/master""
            }
        }
    }
}";

        var bodyContent = new StringContent(bodyJson, Encoding.UTF8, "application/json");
        var pipeLineId = 61; // Can get this from URL when you open the pipeline of interest in Azure DevOps
        var response = await client.PostAsync($"https://dev.azure.com/ORG_NAME/PROJECT_NAME/_apis/pipelines/{pipeLineId}/runs?api-version=6.0-preview.1", bodyContent, cancellationToken);
        response.EnsureSuccessStatusCode();
    }
}