Hi @havamarie7 with Convertkit you do have an option to sell digital products but you may need to create your landing page to sell the digital product and set up the payment.
Convertkit doesn't have an option yet where they will be the one who will sell the product for you and do all the set up.
But if you want to checkout the Convertkit Commerce feature you can check these link:
ConvertKit Commerce: Overview + FAQs2
ConvertKit Commerce: Creating a Product2
I hope it helps. If you further questions you can always reach out to firstname.lastname@example.org.