You still aren't going to ship all those unnecessary types in your production app, so you'll be creating a complicated pipeline anyway. The big difference here would be that your pipelines will be radically different, so you wouldn't know about random breakages in the development pipeline until you deployed to production.

More importantly, this doesn't add all of TS, so you'd still have to run those tools and nothing changes except that JS is now locked in to a syntax that may or may not be the best for an actual type system in the future.