I tried, but I couldn't get it to work at all. I don't really know what I was doing wrong, it just hung without connecting. It's been a while and I haven't tried since.
Same. Tailscale just worked out of the box on all my devices. ZeroTier had issues connecting which I didn't bother troubleshooting because Tailscale just worked.
I have and it works just as fine for me.
TailScale seems to have a better ui and more tooling (File sharing, SSH, ...). Even though those recently led to RCE[0]
When I tried Zero Tier it had trouble with bonjour/rendezvouz/mDNS zeroconf host names. Getting it up and running on a new device was also a bit more complicated than Tailscale (although maybe at the expense of needing to trust TS more than you needed to trust ZT?)