[Cat Food Supplement] Reduce Fel d1 protein in cats through diet

So I met this guy. Great guy. Two cats. I'm not talking mild sniffles. I'm talking swollen eyes, can't breathe, full histamine meltdown within 20 minutes of being in his apartment. We tried everything. Air purifiers in every room. Washing the cats weekly (they hated it). I was popping antihistamines like mints. Nothing really worked long term. Eventually I went down a research rabbit hole and found out most cat allergies aren't actually caused by fur. It's a protein called Fel d1 that cats produce in their saliva and skin. When they groom, it gets everywhere. Some cats produce way more than others. Turns out theres been some interesting research on reducing Fel d1 through diet. Targeting it at the source instead of just managing symptoms on the human side. I got a bit obsessed tbh. Read everything I could find. Started talking to formulators. Long story short I'm actually working on something now. A daily supplement for cats that reduces Fel d1 and supports gut health. Still in development, launching next year. But honestly just curious, has anyone else looked into this? Tried anything that actually helped? Most allergy advice is just "rehome the cat" or "take Zyrtec forever" and neither of those worked for me.