The last OpenAI models, gpt-4.1* (gpt-4.1-nano, gpt-4.1-mini, gpt-4.1) and gpt-5* (gpt-5-nano, gpt-5-mini, gpt-5), are available to be used at translate.wordpress.org. To use them, you need to select one of them at https://translate.wordpress.org/settings/

Pricing
You can check the API prices on the OpenAI website.