Hey @Federico_Ciuffardi,
Welcome to the MongoDB Community!
As per my knowledge, you cannot resume the M0 cluster using the MongoDB Atlas APIs. May I ask if is there any specific use case you’re trying to address?
However, Atlas automatically pauses M0 free clusters after 60 days of inactivity where there are zero connections to the cluster. You can resume the cluster at any time by connecting to that cluster using a MongoDB Driver, mongosh, or Data Explorer.
In case of any further questions feel free to reach out.
Regards,
Kushagra