I’m setting up an openhab RPi3 for my church HVAC system to set thermostats based on calender events.
If I use my my.openhab login for that system, can I also create another one for my home system later? In other words, can I have virtually unlimited logins with my username as long as I have different UUIDs?
No. You can only connect one openHAB instance to a single my.openhab account. You can have multiple users on that one account, but not multiple openHABs.