You do not need to use Global Resource Settings in the resource path. The parts of the resource path can be set to be sourced from properties. You should see a grid underneath your resource path control. That is where you map the sources of the "wildcards" in your resource path.
Alternatively, most of the records that use REST Connectors have an "endpoint" field that you can use to specify the URL for the run-time connections. This will override the pyResourcePath property.
I believe that in Pega 7.2.2 you are able to use Global Resource Settings for pyResourcePath, despite this property not being officially documented. it is just less "dynamic" than using parameters for the parts of the URL that are truly dynamic.
As far as I know, the resource parameters mappings do support Global Resource Settings when you set the "Map from" to Clipboard.
Of course, you should do some local testing, no matter which option you choose to go with.
Note by the way that although Jeff is correct that support for GRS with pyResourcePath is *not* documented on the main help page that lists all fields in Pega supported by GRS ( /prhelp/procomhelpmain.htm#concepts/concepts2/globalresourcesettingfields.htm#Fields_that_support_the_Global_Resource_Settings_syntax ), the fact that GRS is supported for pyResourcePath *is* nonetheless explicitly documented on the context-sensitive help page for Connect-REST, at least for versions 7.3.1, 7.3, 7.2.2, 7.2.1, and 7.2 (I haven't checked earlier versions of the help -- the path is /prhelp/procomhelpmain.htm#rule-/rule-connect-/rule-connect-rest/service.htm ):