The easiest way to do that in Penpot is to create a team and add projects as you need them. All those projects and files will be available for your team and you will be able to work either asynchronously or simultaneously.
A Penpot user can be part of many different teams and have access to all their available projects.
Of course, Penpot also gives you the possibility to work on your private projects or drafts.
I’ll share my typical use case (I’m a developer/CEO so it might be a bit different from other people).
I like to draft some ideas visually. I find myself not needing google spreadsheet anymore. I just use Penpot for presentations or more freeform concepts I want to share with people. I do this under “My Penpot”. Sometimes I use the Drafts section and some other times I use an existing Project. This is my private space, like my personal white board where I explore random stuff I don’t feel comfortable sharing just yet.
At some point I want to start working together with other people so I move it to the Drafts section on a different Penpot team project.
That makes it visible to anyone on that team but still says “I’m a draft!” so collaborative editing is welcome but not encouraged. After some time, I move it from the Drafts section to its relevant project in that team and that’s the time where I normally present it to the team on a videocall and it’s now “officially open for contributions”.
In a nutshell, I go from “my private space” → “visible to the team” → “open for team colaboration”.
So far I haven’t needed to do the round trip, but if I ever saw some project files begging for being archived, I would probably move it back to something like “Archived projects” under My penpot space.