New house, need WATER SOFTENER

[MichMich]

Building a new house in S Texas. We have very hard water here. Need to install water softener.
I have two water heaters (40 gal each) and a pre plumber for water softener pipe.

1) what water softener should I install, 6 people household
2) are the ANY good ones SALTLESS ones?
like this one:

Capacitive Electronic Water Descaler System - Alternative Water Softener Salt Free for Whole House, Reduces The Effects of Limescale [CWD24, Max 1" Pipe]​

https://www.amazon.com/dp/B07X7XYKR...
Any tips and advice GREATLY appreciated.

Thanks!
Michael