When researching flying with a nut allergy, I found many negative Eurowings stories. However, I want to put this out there to say that in my personal experience (7/2019)they were not bad.
On our first flight, the staff at the gate made two announcements asking people not to eat peanuts, and personally took us onto the plane to help clean our seat. The staff then talked to the crew who said it’s “against company policy to make an announcement” (not clear what is official) but at least the ground staff were helpful).
On the second flight, the crew let us board early, came and asked how how bad the nut allergy was (if it was ok for them to continue sale of nuts, and if we had medicine in case of an emergency) and then happily agreed they wouldn’t sell nuts for the flight. They also asked if I was feeling all right multiple times on the flight.
From our experience, and what Eurowings support told us, it’s completely down to the flight crew. If you approach them politely and don’t demand, both times someone did their best to help us. Personally I would be all right flying with them again. (Not sure if someone with an airborne sensitivity would be ok).