Do a web search for brief notes, short articles, and commentaries for journals in your discipline and related fields. Many of these sections of journals are peer-reviewed.
You may have to dig a bit to find them.
Here is one example from the journal International Social Work. You will notice it is in the "Manuscript Submission" section under "Article Types." For this journal, brief notes are up to 2000 words long.
How long would it take you to write a brief note about an "unresolved problem" (one of the areas of interest noted under this guidance) in your field?