Custom GPT vs. Assistant for a specific task

Hello everyone, we have quite specific situation and I would love to ask for some advice. We have a database of 50K+ products and would like to integrate to their descriptions some Chat GPT generated texts, created using some specific guidelines.

The only choice that seems feasible is to create an assistant and link it trough the API with the backend. BUT - we only need to run the process one time - once all the texts will be generated we don’t plan to review them.

Investing into the assistant creation requires some time and skills while creating a custom gpt seems an easier option. But as I understood, there is no way to get an output for 50K products from custom GPT, unless doing it manually, and the capacity would be 40 products per 3 hours which would be 5.5 months of 24 hours non-stop communication with a custom GPT which makes it hardly feasible.

What I heard about the Assistants is that they can’t access the internet, unlike custom GPTs, or at least there should be an additional development related to that.

Are there any other ways to do this task or the Assistant is the only possible choice?

Many thanks for your advice!

10$,i can do it for you, just tell me the detail requirement