What counts as a digital product
A PDF, a preset pack, a template, an audio file, a key, a link to a members area. Anything the buyer receives rather than waits for.
Delivery is the whole product
With a physical item, a slow reply is annoying. With a file, a slow reply is the product failing: the buyer paid for something immediate and got a wait. Attach the file or the access text to the product so it goes out on payment and not on your availability.
Telegram Stars, when you want no payment plumbing
Digital goods can be sold for Stars, the in-app currency. The buyer pays with Stars inside the chat and the Stars land on your own bot balance. There is no payment provider, no card processing and no cut taken in between. It needs your own bot and a paid App plan.
Price it for what it saves, not what it weighs
Nobody can compare your file to a shelf price, which is freeing and dangerous. Say plainly what it contains, how long it is, what format it comes in. The most common reason a digital product is refunded is that the buyer imagined something else.
Write the description a buyer can check
Format, length, what is included, what it does not include, whether updates are part of it. A list of facts sells a file better than adjectives, because the only question the buyer has is whether it is the thing they need.
Set it up once
Add the product, attach the file or the access link, and place a test order yourself from a second account to see exactly what arrives. The storefront is described on Telegram Mini App store, and the plan limits are on Pricing.