I personally dont see a way to apply registry scanning to only a subset of devices. However, I would recommend having the registry scanning set up, and then you could craft a report that only includes the devices that you want. For instance if you want to scan the registry for 'whateverspecificsetting' on Windows Server 2019 only, you could write a quick report to pull that info. If you setup the registry scanning for "whateverspecificsetting" across the board, if it doesnt see it for a device, it just wont pull it.
For instance, we have a registry scan setup to pull the last date the asset was deployed with MDT. That registry scan applies to allllllll assets in our org. But if it wasnt deployed using MDT (say, hand built), then that registry key just isnt there:
MDT built:
MDT *NOT* built:
Lemme know whatcha think.
Thanks