I hate etcd with the best of them, but etcd is used in a lot more places than just kubernetes:
https://github.com/apache/apisix/blob/master/docs/en/latest/...
https://github.com/traefik/traefik#:~:text=Etcd,
https://github.com/zalando/patroni#patroni-a-template-for-po...
https://github.com/purpleidea/mgmt/tree/0.0.26/etcd (this one shows up on HN quite a bit)
https://github.com/sorintlab/stolon#features
It's actually one of the major reasons I wouldn't touch those projects