Got a reply for cshields on IRC so I’ll share it here in case anyone else had a similar question.
cshields I don’t know if the client will run without the api key but the other day you asked this in regard to the rotor/arduino - which you can run and operate without the client
cshields set up hamlib (rotctld) as you would for satnogs, and then you can connect to it with another tracking program like gpredict
cshields this is handy for testing the rotor itself
cshields but if you want to test satnogs client specifically, I would suggest signing up and grabbing an API key from network-dev.satnogs.org
cshields that is a sandbox site so there is no harm in connecting there while getting things going