I know for sailboats there is bottom paint that makes it flow through the water faster. Does such a thing exist for kayaks and does anyone use it?
Coatings
Most sailboats live in the water and need some kind of bottom paint the “fast” ones are the lesser of the evils. There is a Teflon bottom paint used on some high speed motor boats. A fine sanded coating of epoxy/graphite is thought by some to increase laminar flow…
No mater what you put on the bottom the person with the best forward stroke wins…
bottom paints
racers who CAN keep their boats out of the water often will, since it allows them to keep their hulls cleanest and smoothest, without gunking them up with antifouling paint. The paint you’re probably thinking of is VC-17, which is a Teflon-based anti fouling. It’s faster than traditional copper/tin bottom paint, but only in relation to those finishes. Unless you’re leaving a yak in the water all summer like a boat, it isn’t going to make you faster - just heavier and messier.
bottom paint
is not for speed, unless you consider that without it, in a marine environment, your hull will be covered with barnicles and seaweed shortly. Most of your big budget raceboats, power and sail, are stored on land and get the advantage of not needing bottom paint.
On the other hand
I’ve been told that the US Navy uses a “coating” on their submarines that increases the under water speed by something like 10 knots?
Of course I seldom paddle my kayak under water 
Thats funny.