Default theme source - yarn instead of npm

Good morning,

I started a new theme and for this I take the Source theme as a basis.
So far I have always worked with npm, the source theme uses yarn.
I find yarn a bit more complicated and have not yet managed to get it to work. It always breaks at

run development server

yarn dev

Is it “easy” to convert the theme to npm or is it complicated?

And why are there two “standards” at all?

Thanks!
Martin

No difference

npm run dev
yarn dev

both works for me.