https://itch.io/t/253885/help-us-make-devlogs-better-what-should-we-do-with-this...
The devlog subforum is basically deprecated, except for some special cases. Also, you will not be visible in https://itch.io/devlogs
You can publish an unfinished project. Or at least make it accessible. While I do not know if this is a requirement to have devlogs that you upload any files or have any special accessibilty options. I seen project pages without any files or placeholders. But I would imagine since a devlog contains the link to the project that it might not work, if the project is restricted such that only the creator can view it. If it is merely restricted as in, not indexed, that would not be a problem, but it might also not put the devlogs into https://itch.io/devlogs .