What open access textbook publishing initiatives are around? [on hold]

I am wondering how open access textbook publishing platform is viewed in regard to publication turnover i.e. how quickly can one get published through it, compared to (say) traditional publishing?

There are several open access models and I am aware of Open Suny which describes itself as follows:

Open SUNY Textbooks is an open access textbook publishing initiative established by State University of New York libraries and supported by SUNY Innovative Instruction Technology Grants. This pilot initiative publishes high-quality, cost-effective course resources by engaging faculty as authors and peer-reviewers, and libraries as publishing service and infrastructure.

This is a peer-reviewed platform (so it is different from self publishing).