I understand your dilemma. I live in Luxembourg which has the same “forced” inheritance laws as France.
I have three children who live in 3 different countries,
Frankly a trust is expensive and can complicated when you have gone.
I feel you want to protect your child in death as you probably have in life but I suggest you just leave it to fate.
That is what I have done.
Inadequate kitchen equipment in holiday accommodation.
