I've been researching under sink water filters, connected to a dedicated drinking faucet, that goes next to the main kitchen faucet. It's hard to really conclude exactly what you're getting which each filtering option.
As for the minerals being taken out during filtering: if it's RO (reverse osmosis), most provide an end stage that puts the minerals back in; if it's not RO, the claim seems to be they never take the minerals out to begin with — the reason for a high TDS (total dissolved solids) reading. Arguably, as a result of attempting to keep the minerals, are other things remaining that are questionable?
So far, for a budgeted price, it's hard to find a system that addresses everything: chloramine (makes tap water taste bad, but it's not in all states, regions), microplastics, maintain minerals — just to name a few. For the lower end, budgeted systems, it's an either or situation, I'm finding. It's either a focus on microplastics or chloramine, but not the best filter for both.