Simplest possible product idea?

Hi!

I wondered what people's thoughts were on the simplest possible product ideas with the least number of integrations/tools?

I understand you could have an info product in just Notion, or a landing page in Carrd for example as a stand alone product or idea, but what would be the simplest 'dynamic' or integrated product that you could have?

For example, connecting Calendly to Carrd to schedule appointments would be one.

What are some others that people think of?

Thanks