I am working on a commentary on the Psalms. I have decided to compile some helpful links that I discovered during my research. It includes a mix of exegetical and sermonic links. Here is what I have for Psalm 133 (in no particular order). Feel free to mention any that you find helpful in the comments section.
Nancy Koester: https://www.workingpreacher.org/preaching.aspx?commentary_id=274
Analysis by C. J. Labuschagne: https://www.labuschagne.nl/ps133.pdf
“Pilgrim Unity” Bruce Waltke: https://stjohnsvancouver.sermons.io/sermons/pilgrim-unity
William Barrick’s notes: https://drbarrick.org/files/studynotes/Psalms/Ps_133_134.pdf
Psalm 133 devotional: https://www.generations.org/devotionals/218
Doug Bratt’s commentary: https://cepreaching.org/commentary/2015-04-06/psalm-133-3