What would you advice about packing electronic devices (mobile phone/camera/GPS) in a dry bag or TPU Pouch?
Regardless of manufacturer, no roll top dry bag is waterproof enough for long-term, problem-free storage of electronic devices. Factors such as period of exposure and external pressure can let even a very small amount of moisture damage electronic devices.
It is very important that you conduct a waterproof test on the dry bag or pouch BEFORE you pack a camera or any other gadget in it. Doing so will help you learn to closely follow the instructions on how to seal the bag or pouch, and ensure that the bag or pouch has no factory defects, has not sustained any damage from the last time you used it, nor sustained damage from long periods of storage.
If you are going to take your precious electronic gear into a wet environment, or tough terrain (or both!), make sure the dry bag is robust enough for the activity you intend to do. This is why we have chosen a substantial rip stop fabric as the main material for our dry bags. Together with a TPU coating (thermoplastic polyurethane), our dry bags are designed to resist abrasions, stay flexible in low temperatures, and resist heat, oil, and even fungi—properties which run-of-the-mill PVC dry bags and super light-weight dry sacks do not possess.
In heavy weather or super rough conditions, we even recommend that you double-bag your electronic devices—i.e. place the item in a dry bag, roll and fold the double-barrier closure, click the snaps into place, and place it all in a bigger dry bag which is to be rolled, folded, and clicked shut as well.

For a simple, light-weight, and submersible option for electronics, we recommend our TPU Dry Pouches, these pouches use a hard ABS plastic with locks that provide an excellent waterproof seal. Properly closed, these pouches are excellent for boating use – they are tested for up to 19 meters of submersion for 30 minutes, earning an IPX8 rating. The rigid closure cannot accidentally pop open by itself.
It is useful to place a desiccant sachet inside the dry pouch to absorb moisture. There might be a temperature difference between the outside and inside of the casing, especially when used in cold water, which can result in a slight build-up of moisture or condensation.