Do you know any disinfecting powder available as a speciality (for open wounds); Or a suggestion to make it into the pharmacy?

There is indeed no more speciality. Now self-preparation is not unsurmountable. With the exception of Mg or Znstearate, most excipients for stray powders are sterilizable at 150 °C, after drying at 110 °C. One can do this in a sealed recipient, which is placed in a hot air oven. For open wounds, one uses lactose (see Galenic Formularium, Hfdst Sprinkle powders). I would not treat the disinfectant with heat but to process it aseptically in the excipient. A mortar, which we clean with an antiseptic detergent (diluted Dettol) and drying at 100 °C, can also be sterilized at 150 °C together with pestle and spatula. The big problem remains the powder canister. A glass jar is sterilizable with a simple sterilization method. Possibly in a hot air oven or autoclave. Restriction of course for the Bakelite lid, which can certainly not be sterilized at 150 °C. Probably at 120 °C. Plastics powder cans are only sterilizable with gas. I don't think they're sterilized to be negotiable.