You can enroll as many devices as you need for demo purposes as you need in demochrome.com.
Devices can be powerwashed/deprovisioned if you wish when you have finished the demo.
Devices you enroll with your provided account, will be placed in your user org unit.
You can move these into any of the pre-configured Device Org Units to demo different features on demand.
Polite Request: Please deprovision devices selecting 'same model replacement' when you are finished using a device on the domain.
Advice and Top Tips
Each partner has their own Sub-Org Unit for each Device Org Unit. Every time a colleague signs up they will be added to the same OU. You can then choose to make specific changes to your OUs and all of your colleagues will experience them.
If you as an individual want to make specific tweaks, we'd recommend you create additional subOUs with your name.