Just a short point. Conservatives talk about H1B visas being used to bring workforce that doesn’t really match the criteria that is defined in the H1B terms. It is possible, and I agree sometimes it happens.
But you need to understand that the cancelling H1B will just mean that the companies will switch to a remote, online workforce. No options for taxation and the money paid to a person will not fall into the pocket of a local hotel, grocery store or a barber.
You can not protect technology jobs inside the US by not letting people in to the country. People will just work remotely. The possibility for remote work is available for designers, engineers and basically anyone who uses computer to produce some unit of work.