The ability to create multiple Workspaces is an experimental feature that is available in the Pro plan subscription (by request).
In Sidekick you can access multiple accounts by setting them up for certain apps. But what if you want to separate environments completely? For example, separate your home from work. You can do it with Workspaces!
Workspaces are different work environments with independent dock and applications. All applications in a given workspace share cookies among themselves and are isolated from other workspaces, so you can use workspaces to separate accounts between different environments, "e.g., Work / Home / Side project" and switch between them. Workspaces also retain your tabs so that your work is saved when you switch over.