I think that's what I would called widget. IMHO, React is a poor choice for such thing because of its size (react + react-dom is about 30 KB last time I check). I usually use preact-habitat to do this
Thanks for the answer! It doesn't really matter if it's a poor choice, as that is also something I could look at and compare between technology choices for my project. Would npmjs.com/package/react-habitat be the equivalent in React? If so, I could take a look at both.
So I could just code my different Pagelets/Widgets as seperate components and use ReactDom capabilities to mount all of them into several DomNodes in an empty "container" web page to assemble my website out of them in React?