Sorry, we don’t have any published guidelines or even any internal benchmarks for this kind of thing. It’s also going to vary depending on which driver you are using.
10,000 devices is an order of magnitude more than I would recommend. We’ve seen a couple hundred up to maybe a thousand, but the current architecture of the drivers doesn’t lend itself to many more.
There’s also an issue of how to configure the devices in bulk, both initially, and to when it comes to maintenance/modifications.
In the future I this will change, starting with the Modbus Driver, but the timeframe for these changes to start taking place is something like 8.1.