Why would it increase supply? You've reduced international supply in exchange for increasing domestic supply.

Promoting internal business isn't a sure thing - particularly when tariffs reduce competitive pressures.

Reduced competitive pressure is a boon to business.

The less competitive pressure there is, the more likely it is that new businesses will form -- it lowers the bar and makes it easier to start new ventures.

The first part is arguable, the second isn't - it just isn't true. Usually, you get large, monopolistic industries that are propped up by the state. So worse products and services than what's available internationally for higher costs as you don't have to compete against all comers. Only a few countries have ever escaped this trap - there's a great Odd Lots about it: https://podcasts.apple.com/us/podcast/this-is-how-industrial...