What happens to your pets if you die?

I wrote a will. I'm not a Belgian citizen yet, but have not asked for the will to be executed by my country's laws, so afaik Belgian laws apply.

In my will I put a list of people in order of priority who should take him. But I assume this won't be looked at in the immediate aftermath of my death, so what happens to my cat?

I would die at home, all necessary papers (deed, will, cat papers) would be clearly and visibly laid out on my kitchen table. If I write a separate paper designating where he should instantly go, would that happen? I don't want him to go to a shelter, not even temporarily

If I have no other option I could drop him off at someone's house before I die who might not keep him, but would not abandon him and has plenty of room to have him in his mansion.

EDIT: I appreciate whoever it was that reached out to reddit care, I do. My life would be too long and a serious downer to explain, so I'll try and give the very short version: 20 years of mistreated depression that ~6 months ago was diagnosed as bipolar 2.

I have been through a lot of trauma. 2 previous attempts. I am fully medicated, and was stable for 2 wonderful months. Now I'm back where I was. This is a question of when, not if. I am alone. But my cat has been my reason for trying to stick around the last 6 years (when I adopted him), and I need to know that when I can't go on anymore, he will be safe.