If you want to use the Chirpstack ecosystem, you firstabel need to make sure that you are using of the packet forwarders backend that Chirpstack supports. Once you have verified this, you must decided how to deploy each component (gateway-bridge, network server and application server if this last point is required in your specific use case).
Technically, you won’t be able to connect right away your end node devices to Chirsptack with changing only keys.