From the compose mpp page:
https://www.jetbrains.com/lp/compose-mpp/
After the inscription
Compose for Web Features (same with desktop)
There is a See All Features button, when clicked, it should throw on a file with a description of the features, but in fact:
“The ‘JetBrains/compose-jb’ repository doesn’t contain the ‘FEATURES.md’ path in ‘master’.”