I haven’t migrated my 8.1 automated deployment yet, but I’m not anticipating any showstoppers.
I reckon I’ll add myself to the list, and echo to start with a gateway backup. Configure a single gateway in the UI, then use that gwbk for all future gateways. The gwbk can be restored via script (immediately following your automated install), and would contain the base config for your client - things common to every gateway. With any luck, that could include MQTT configuration…
Personally, I’m not a believer in Docker for bare metal Edge installs. To each their own…
Regarding the API key:
Regarding any other specific hurdles you encounter, inquire here.