It will certainly not harm your chances of getting a job but it will harm your ability to receive unemployment benefits from the government as they will conside

It will certainly not harm your chances of getting a job but it will harm your ability to receive unemployment benefits from the government as they will consider the business equivalent of a full-time job. You can start a sole trader business easily (and cheaply). In many EU countries there is a scheme where students or full time employees can start side businesses as sole traders and not be liable for VAT and social security taxes. I am not sure if this exists in Portugal but you can check with your local bureaucrats. Activity like this will increase your employability in most companies. It can be an issue in government regulated businesses such as insurance but they are used to telling employees to shut it down.. it's a non-issue for hiring.