postnik0706 You are welcome either to use subaccounts to split PROD/DEV data or you may use multiple totally separate flespi accounts. The price tag should not be that large.
For the DEV/QA accounts you may use flespi gateway stream type to copy full set of input data from one flespi system into another.
For the testing control lines from DEV you have no option, but to use separate device.
Subscription topics should be configurable per each installation, so all our IDs should be either dynamically retrieved with REST API from flespi or written in the system configuration somewhere.