Interesting question. I don't have a definitive answer but I'd guess no. We know that there was contact pre-colonisation between indigenous communities and Indonesian fishermen. The fisherman would sail to Australia's Northern Territory (NT) to fish for a type of sea cucumber that they then converted through a long process into salt & took back to sell to China. Logic would suggest that if there was a robust salt trade already existing between Indigenous communities it would have been far more efficient & economical for the Indonesian sailors to have just traded for the salt to on-sell to China rather than having to stay on the beaches of the NT to do the process of harvesting/fishing, cooking, burying, drying & smoking sea cucumbers to turn into salt themselves.

Edit to add:

if they needed salt, wouldn't they have obtained it from Halite deposits or ephemeral salt lakes

Again just a guess but I think it's more likely they'd have gotten salt from intermittent lakes - i.e. lakes that are dry part of the year (so a regular annual thing, not an ad hoc drying up as a response to water shortages like in ephemeral lakes). There are communities & farmers now that do this with intermittent lakes in Aus to get a type of (very tasty) pink salt but it's a very labor intensive job to do manually (which, again, makes me think it was unlikely for hunter/gather communities to have done but just guessing).