Potassium = Bronners liquid soap
Sodium = Bronners bar soap
Both dilute same in water which you have to do before applying to plants so makes little difference?
You are not consuming it, so it matters little, use what is available,
and/or cheaper?
I don't really know, hard to find ingredients in stores here in US, have to look up drain cleaner ingredients online before buying from Home Depot. I used a potassium hydroxide 45% / water 55% drain cleaner that worked, but I question the water?