atm there are 2 public instances https://gitnostr.com and http://relay.ngit.dev running the experimental reference implemention. The idea is that people use multiple public instances and self-hosted their own.
Discussion
Is distribted git servers the right model? or stick with the traditional 1-to-1 repository-server approach?
https://ngit.dev/relay/#vision
existing ngit users should upgrade to v1.7 https://ngit.dev/install