I think you are doing great with the wound.
Rather than using purified water to bathe the wound I suggest you use salt water as it is mildly antiseptic. Use 2 teaspoons table salt in 1 cup of boiled and cooled water. Alternatively use 2 sachets of salts sold in pharmacies for sinus wash outs using a neti pot, also in 1 cup of boiled and cooled water.
One suggestion for keeping the wound clean now would be to spray it with liquid skin. One brand sold in pharmacies is
https://newskinproducts.com/
If there are any broken bones, the duck needs prescription antibiotics as there is great risk of bone infection. The only way to be certain regarding broken bones is by Xray. If there is any chance you can get a vet appointment, I woudl do so. Snapping turtles of break ducks legs -- our local rehabbers get them every year,
Keeping your duck quiet in the home is a great idea. If she has not needed pain killers until now, don't worry about pain killers.
Do let her swim frequently in water deep enough to swim not just move around. That is good physiotherapy without weight bearing.
If you can't get an Xray, wait until the swelling has gone down and see if there is obvious deformity. As others have said, its possible to feel a bad fracture but be careful as its possible to displace a fracture with palpation. If there is no obvious deformity, and no acutely painful place indicative of a fracture when you gently feek the leg and foot, let the duck begin to move and weight-bear when it is ready: that could be in 2 or 3 weeks.
I would be relucant to spint the leg unless a fracture is obvious, as it is possibel to do more harm than good with a splint