Tbh I'm knitting them with cotton twine because it works and we don't really have the cheap buck or so a pop cotton yarn here. (And I don't particularly like this brand of twine, preferring the one I used to use.)
I've looked to other proper projects but things are a bit dire for yarn in Australia. Not a great selection and ordering online can often be met by unavailability/won't ship/prohibitive costs
My whole life I've just been remathing everything or going full experimental to use what I can get.