.Net Core V2.2 - Sending email or gmail using OAuth2 or secure settings in Gmail in the background without browser auth

I thought this would be pretty simple to do, but has turned into a circular headache.

It's hard to find info on the internet on this subject, for most are using MailKit and MimeKit, others using SendGrid.
Plus I read that SmtpClient has been obsoleted as well with MailKit being reccomended.

So I have my secrets file working,
My Google OAuth2 Credentials have been tested and works.
Altered my Startup.cs to add Google credentials to services.
Altered my Startup.cs to services.AddAuthentication().AddGoogle
I did the example that opens up the browser to a Google Auth Page, writes the token with successful auth.

So here is my circular headache ....
Using Nuget MailKit/MimeKit, it doesn't register with .Net Core V2.2
Using Nuget SendGrid, same thing, doesn't register, get the caution or warning icon in dependencies nuget.

I can do this now, but I don't have any code to actually send the email.

var secrets = new Google.Apis.Auth.OAuth2.ClientSecrets
{
    ClientId = Environment.GetEnvironmentVariable("GMailClientId"),
    ClientSecret = Environment.GetEnvironmentVariable("GMailClientSecret")
};

var googleCredentials = await GoogleWebAuthorizationBroker.AuthorizeAsync(secrets, new[] { GmailService.Scope.MailGoogleCom }, email, CancellationToken.None);
if (googleCredentials.Token.IsExpired(SystemClock.Default))
{
    await googleCredentials.RefreshTokenAsync(CancellationToken.None);
}

I'm not sure which way I should proceed.
I can't find any references, or documentation for .Net Core V2.2

I must admit that the SendGrid SAS looks pretty cool for sending email from my website.
Any help would be appreciated!