One has to be careful playing with free hydrogen. It is explosive -- recall the Hindenburg disaster.
Hydrogen's not explosive, it's just flammable.
Hydroxy/Brown's Gas/HHO/etc ... is quite explosive. When you split H20 into 2H2 + O2, it exists in the perfectly explodable mixture (to turn it back into water, releasing the energy as pressure/heat that you spent with electricity to tear it apart in the first place).
Hydroxy generators are a regular snake oil / conspiracy theory from the free energy crowd. All kinds of BS claims about how they massively increase your mileage.
The Hindenberg mostly just burned like a campfire until right near the end when the hydrogen mostly ran out and the fuel-air mixture finally tilted far enough towards the oxygen side. It had time to crash land, crumple, most of the passengers to run away, everyone to watch it sit there and burn first.
Fun fact, HHO is also lighter than air. You can fill balloons with it and they'll float. You can tie a string to the balloon and light it on fire before you let go of it. It'll get a few hundred feet high before it detonates. When you fill a balloon with hydrogen and pop it with a flame, it makes a Whoof sound and you can feel the heat. When you fill a balloon with hydroxy and do the same, it BANGS and you just feel a shockwave.
Table salt is a poor chemical to use to make the water conductive. A side reaction of shoving electricity through it, is to give enough energy to the chlorine atoms (sodium-chloride being table salt), to bond and bubble up as poisonous chlorine gas. Turns the water green and is so intensely corrosive even stainless will be consumed in seconds. Battery acid, TSP, or even baking soda is less troublesome. Two stainless spoons on a car battery charger each, dunked into water will make bubbles that pop.
This is a possible fueling method (IE hydrogen powered cars). The problem is it takes a lot of power to split the H2 from the O using electrolysis.
It's decently efficient to generate the gas, there's not that much waste heat unless you're greedy and try to speed the reaction up by cranking the voltage above what's needed to electrolyze the water (does make it go faster, but a bunch of the extra power goes into heat and creating steam bubbles).
This is why, even for hydrogen-powered vehicles that Toyota's been working on for 15 years, the service stations don't use electrolysis to get their hydrogen. They take methane (CH4) and crack it to release the 4 hydrogens atoms. More cost effective. But what's even more cost effective is to just burn the methane (natural gas) directly in the engine.
I still sort of have a plan of creating a small (maybe car-sized) autonomous hydrogen blimp that never needs refueling. Solar panel on top, a needle to collect humidity and drip it into a small chamber that electrolyzes the water, and a hydrogen collecting bladder to replenish the gradual hydrogen leak. Batteries and fans for propulsion. Airborne indefinitely.