Stash was an inspiration for K8up. Unlike Stash, K8up is non-intrusive and doesn't add additional containers to Pods. It runs as k8s jobs besides the application Pods.
K8up currently is optimized for PVs and will probably be able to backup objects in the future. It's not meant for cluster disaster recovery or full-cluster backup. (Deployment artefacts should anyways come from GitOps)
SomaticPirate, Stash can backup individual workloads, PV/PVC or any application (Databases or custom including K8s cluster) with the most recent release.
I actually have a cluster that I need to tear down and do disaster recovery practice on, but didn't know how, so I'm still paying for the "important data" that I generated on it.