You can replace the whole build process for Yves in the package.json with the build process of your JS SPA.
In addition replace public/Yves/index.php with what ever you need to serve your SPA.
That will not require any changes to the containers or replacement of the docker/sdk.
We have forked the docker/sdk privately for one project to remove yves and replace the search appliance and it was a burden to maintain this fork and keep it up to date with the original docker/sdk. So if not explicitly necessary I would advice against forking the docker/sdk