The RO system is dependent on the membrane. Theres a level of standardization for membranes and pre-filters. This is an example: https://www.freshwatersystems.com/products/axeon-5-stage-ro-system-50-75-gpd Conversely, there’s a lot of branded systems that require special format filters and membranes (https://www.premierh2o.com/ro-pure-plus-voc-system), which can naturally only be sourced from the manufacturer. A good 4-stage system can be sourced for about $200 give or take.
RO was developed to desalinate water. Therefore, if you use a salt-based ion exchange water softener (the standard water softener) and then run that through an RO, it’ll be a pretty straightforward process. The more pressure you can provide up front (within the specs of the system), the more efficient the system will be. (Actually, it’s the pressure differential that really makes a difference, so if you’re pulling out one cup at a time, it’s less efficient than pulling out a litre). If your water is very hard, there will be more brine produced. There are ways to minimize that waste (effectively by injecting it into the hot water supply), if that’s important to you.
A distiller will have the same problems any boiler will have.
I’ve got a softener and a RO. It comes in between 450 and 550ppm and leaves around 30-70ppm. You typically want to see a >90% reduction; less than that and the membrane needs replacing or you may have pressure issues.
Putin is personally immensely wealthy and, additionally he effectively controls the economy of Russia. Trump is neither - his personal assets are dwarfed by half a dozen Americans alone. Plus as @[email protected] says, he likes the attention and it doesn’t take much to stroke his ego.