What is some of the most hydrating (not moisturising) products you have ever used?

Recently discovered that my extreme oiliness is largely due to my dehydrated skin and looking to find some stuff that increase hydration. Particularly toners/serums/essences/etc but also moisturisers. Very happy with my Cleanser.

Very open to Asian products too as I have heard great things about Korean and Japanese toners.

I also ordered the ISNTREE green tea toner the other day because it looked cute 😖