For me it was just trial and error and copious use of IDE hinting to figure out the nuances of various import forms. You find out pretty fast what doesn't work, then just gotta figure out what mistake leads to what part not working.

As far as the tsconfig goes, I'm with you there; the documentation is a little chaotic and a lot unhelpful. What I have learned to do is start a fresh one every time, enable the strictest settings I can, set up my source code and output structure explicitly (outDir, rootPath, etc.) based off of the comments in a fresh tsconfig.json file, and then leave it alone.

From the various blogs and forum posts I've seen, most people get tied up because they insist on adding all kinds of additional tooling up front. Babel, esbuild, snowpack, jest, the list goes on. Don't do that. Maybe later, if needed, but honestly tsc does the majority of that stuff just fine. Don't prematurely optimize your build and deployment timeline if you can't get imports to work yet.