RE: Activate store commerce DA3011
If you don't have a cloud hosted CSU, you can install install a self hosted Commerce scale unit. You can connect this Commerce scale unit to a tier 1 dev environment (FnO) or tier 2 sandbox (FnO) for initial configurations and pushing the data into the Commerce scale unit. Once you have activated the POS, then you can continue to work even if the FnO is turned off.
Ref: docs.microsoft.com/.../retail-store-scale-unit-configuration-installation
For retail development, we install self hosted Commerce Unit + Modern POS + Visual Studio on a Windows 10 Azure VM which is very effective.