Program.cs

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using OpenTelemetry.Metrics;

var builder= Host.CreateDefaultBuilder(args);

builder.ConfigureServices(s =>
{
    s.AddOpenTelemetry()
    .WithMetrics(metrics =>
    {
        metrics
            .AddMeter("MyCompany.MyApp.*");
    });
});

var app = builder.Build();

app.Run();