I applied it to a washed and polished car with a buffer. Anyway, the car was already shining amazingly. I applied this product additionally. I put about 10 drops for the surface of each door and about 20 for the front hood. It became even shinier and the result is stunning. If it works as a paint sealant as it claims, it should last for many months and maintain the excellent visual result. I'm waiting to see how it will be after the winter conditions and I will come back...
For now, I declare myself satisfied!

Update 1/5/2024
After the winter, the shine is still maintained to a great extent.
The hydrophobicity remains, but not as immediately after polishing. The truth is that in the meantime, the car was washed 5-6 times with a pressure washer and foam. It definitely needs another application in 6 months to have the perfect initial result, which only an experienced eye will notice...
I don't know if professional paint sealants last the same or longer, but for an amateur enthusiast, it does a job that lasts for months and without prohibitive cost.

So far, it has done a really really good job. It polished the entire car and now, as for the durability, I don't know yet, time will tell