A water softener is usually installed at the source (as in, on the pipe that comes into the building/unit) so you'll have soft water throughout. You could get a single faucet softener like the below, but there's filters to change and this one is limited to 22 grains per gallon of hardness removal, which isn't that much. And it's expensive enough.
https://www.amazon.ca/dp/B003TIC1KM
For example a small whole-house softener can remove up to 95 gpg and has no filters to change (just need to add salt): https://www.canadiantire.ca/en/pdp/whirlpool-30-000-grain-water-softener-0621004p.html#srp
And you may already know, but lead plumbing is pretty bad for you.