That changes now, with the developer revealing a release date of April 16th, 2019. On that date, players will be able to purchase and play Dreams in its early access form and, once a full release happens (at a yet unknown date), will have their access and progress carried over to the finished product. Unlike a large portion of the recent Creator Alpha/Beta, there will be no restriction to sharing or streaming content during early access either.
Dreams Early Access will go on sale for $39.95 on April 16th exclusively through the PlayStation Store and in limited quantity. MediaMolecule have published a detailed post about the release over on the PlayStation Blog.