Hola and welcome to the forum
I read your post and although I do not suffer from anaphlaxis I became interested and have just now read up a little online.
As you write the countries you are walking in use a lot of the products you are allergic to, but I think this could be valid for many countries.
A lot of countries probably use similar methods and ingredients so I think a way to approach your walk is to do as you normally do at home, and focus on cooking your own food.
Although this can sound like a major struggle, I remember a diabetic I walked with and witnessed the work he had to endure along his Camino.
A Camino than in his case spanned more than 2000 km, so it was an inspiration to experience his walk
On more practical matters, you should check up on the system in France and Spain, whether the adrenaline pens are prescription only or over the counter sales.
Regardless, I would recommend to bring a prescription from your doctor just in case.
Some countries uses medical passports to bring medicine across borders, which may also be relevant in your case.
Also, I think some written note in French and Spanish stating your condition as well as an emergency guide for a bystander could be helpful.
Finally, when you write that the smell of almond or other nuts can result in an allergic reaction, I am thinking if you should consider walking in another season of the year?
The autumn is the season where exposure may be at its highest.
But then again, I do not know how severe your allergy is and how careful you need to be.
A good thing about the season you are walking in is that there will be plenty of fruits to feast on.
One day at the time and you will be fine.
Happy planning your Camino.
Lettinggo