My well water goes through a whole house water softener, but apparently "dissolved solids" pass through. I once tried a few ounces of distilled vinegar in a gallon or so of water from my dehumidifier* as a final wipedown with some effect, but wonder if it deteriorates a wax finish or otherwise affects trim parts, etc.
Glassware comes out spotless from my dishwasher, so I've contemplated trying a bit of Finish. I think it wouldn't have adverse effects on the car, other than removing some wax, etc. Has anyone here tried this method with success?
Also, I don't wan't to use a hose inline filter, as they need a fairly expensive regular replacement, and perhaps don't remove dissolved solids anyway.

* Essentially distilled water, and I check and clean its filter regularly.

dishwasher rinse aid is a surfactant, meant to change the surface tension of the water...

it causes sheeting of the water, where as all of YouTube wants to show you beading water.... I do not know how it would affect the wax.

I live in an area of high TDS (mainly Calcium) in the water.... I have used R/O water to do the final rinse, but I also have used filter rain water collected in 4 daisy'd rainbarrels at the side of the house to do the wash and rinse with decent results. The TDS of my rainwater was 7-20, depending on how bad the wildfires were.

I haven't yet hooked up my rainbarrels yet for this season.

I collect "distilled" water from my dehumidifier. I check its filter from time to time, but it's not a detectable issue.

The dehumidifier water is for final wipedowns of the paint and glass, using an adjustable plant mister.