Right. You need inferno-compat as a drop-in replacement for react, as well as mobx for all the other vue features.
The payload for that would be similar to vue: 15KB min+gzip for mobx + 7kB for inferno-compat + 4kb for mobx-react = 26KB min+gzip. Latest vue is also 26KB min+gzip
Not really, you also need react-dom.min.js ;) But even then, Vue is sporting automatic reactive dependencies, computed properties, watchers, conditional class names, and other things without requiring a trip to some random NPM package. And it's still a smaller payload than react/react-dom