This is pretty cool.
To summarize the steps (and please correct me if I’m getting this wrong).
You add the “get part of url” column to your table. Let’s say we called that column “roleFilter”. In creating that column, for the URL value, choose “the url of the current page.” For the “part” value you are going to be giving it a name, for example “group”, which will be the parameter name you will use in the url. So for example, In the url you would append “?group=Alpha” if you wanted to filter the page by those items assigned to the Alpha group. In my example the values Alpha, Beta, etc appear in a column called “role”, so we are going to compare that column with the newly created “get part of url column” value to filter our collection. To do that, on the page to which you want to apply this value to filter items you would select your collection, and create a filter for the collection that says “role” column is “roleFilter” column.
Now, as you change ?group= from alpha to beta etc and reload, the collection should change. Did I get that right?