A waterproof phone and laptop would be very nice to have. There are various ways you can go about making something waterproofed. You can coat the components in something or the components have to be waterproof to start with.
Circuit Boards – A circuit board however would need coated because the circuitry is exposed which means that it can be shorted out if it gets wet in a conductive substance like water. Corrosion is also a big issue because of how tiny the metal circuits are. They can degrade quickly which makes shorts happen and circuits burn out and fail. The solution is to coat the board with something. This can be a thin layer of silicone which is insulative and should keep anything off the circuits. Silicone would only deal with liquids however. Perhaps a layer of ceramic would be a better solution. You can also do vapor deposition with superhydrophobic spray by creating a vacuum and then having the device in the chamber and then letting air back in but the air is saturated with the spray vapor. This makes every surface get touched by the vapor which means every surface is hydrophobic now for sure.
Screens – The screens are another big issue but sealing one in shouldn’t be too difficult and using a strong inlaid glass should prevent any issues. However the method of sensory input may be an issue under water even if water proof. Finding a screen that would work would be a big important thing to do.
Ports – Ports on the phone can rust which is another issue. A solution to this is to use electromagnetic resonance to pass the signals and energy along to devices or the ports can be sealed well and made of a material that is waterproof. Copper tends to be waterproof as well as stainless steel. So a number of materials could be used but they wouldn’t be useful underwater unless a rubber seal were included in the design which it would be nice to have.
Power Sources – Battery to device interface is an important one for transmitting power that makes the device actually work. Using electromagnetic resonance the power can be transferred from a special modified battery to pass power from a coil to the phone. A tiny circuit rides aboard the battery with the coil that flickers the power on and off in a specific frequency. This power change allows the energy to be transferred as you can only transfer power from coil to coil if you are fluctuating the magnetic flux between them.