I have never seen pins graded that were not part of a known set. For example, I have seen Our National Game pins, 1956 Topps Pins, and 1910-1912 Sweet Caporal pins all slabbed.
From what I can tell, I have only seen one PM 10 pin slabbed and that is a Ted Williams.
Here is the link to PSA's pop report for pins. I did not search every link, but I did not see any generic team pins from any league in the report. The Williams I noted above is the only PM10 listed as slabbed
Hope this helps.
https://www.psacard.com/pop/pins/20013