Hey! Sorry for the super late reply, I missed your posts; thanks for participating!
I use ZeroTier both for personal and professional purposes.
Personally, it allows me access various home servers whether I'm home or not. I've also used it in the past to get remote access to my father's Linux computer to help him out with some technical issues from the command line. My home setup is pretty "traditional" with the individual devices all having ZeroTier installed on them.
Professionally, it's become the back end for our remote work. We have ZeroTier routers that provide access to the company's existing LAN network resources to employee machines. It's been working really well for that aside from the occasional blip (seemingly relating to misbehaving networking hardware -- e.g., bad hotel/airline/AirBnB WiFi).
I love the flexibility of the system and I'm very excited for ZeroTier 2.0 (hopefully soon).