REST sensor setup "before" installation? (setting up HA for a friend)

Hi, I want to provide a friend of mine with a HA instance, basically put a pre-installed raspberry into the mail for him to connect to his network and finish installation.

Is there a way to pre-configure rest sensors? His main usecase is his solar setup, for which tons of rest endpoints need to be created to talk to the inverter.
I would like to make it as easy as possible, so I’d like to avoid him doing a default setup and then me dialing remotely onto his laptop to then copypaste yaml into his configuration.yaml etc

Is there a way to do this easier? Ideally I’d like to include a pre-configured configuration.yaml as part of the base installation package already.