Can we use compose-html and compose-web together ?

No. You can follow this feature request: https://github.com/JetBrains/compose-multiplatform/issues/3172

This is talking about HTML tag in Compose for web, what about the opposite, Compose Web canvas inside Compose HTML project.

In both cases, it's possible to do manually (but requires a bit of knowledge of the internals of Compose), but there is no out-of-the-box API to do it

Yes. I think nothing stops you from adding ComposeTarget canvas to you compose html page, but i am not sure they can directly communicate with each other.

AFAIK, you can have multiple Appliers reading from the global Snapshot with no issues, but you'll have to ensure their clocks are synced 🤔

Thanks guys, I think that I need to give it a try.

I don't think there is an official tutorial on how to do it… I have studied how other libraries do it (I recommend Mozaic and Turbine)