As Old Adj has said...this topic and many others have been covered in this forum ad nauseum. Please use the search function.
If you get to selection, pass selection, pass instruction, and earn your kepi blanc...then perhaps any diplomas and certifications that you brought might become relevant. Until then, you are (and will be) treated no different then anyone else...no matter if you used to be a ditch digger or a professor of high-energy physics. It will most likely not be of any relevance to your selection.
The road before you become a functional legionnaire is long and hard...you will have the language to learn, military skills to learn and be proficient at, regimental lifestyle adjustments that need to be squared away, and a plethora of other things that will be more prevalent in your daily life than any specialized skills. So the Legion does not assign incoming legionnaires a MOS (borrowing the US military designation), that comes much later.
Finish your EMT training...if you make it far enough in the Legion for it to be relevant again, then it might come in useful. No guarantees...if nothing else, you will have something to fall back on if you do not make it.