Setting up Kubernetes (eg with Talos) really is a one-time investment in the sense that you have to figure out what you're doing (what operators to add, how to connect them to they work together, etc.) and is a valuable skill also for work.
Of course then there's the maintenance - updating operators, Kubernetes, whatever else you have, but you don't have to do it and if you want to do keep up with recent versions then it's just as much work as on Ubuntu or any other distro. The upside with k8s is that you can definitely roll back (I'm just assuming you're using GitOps).
Besides, you'll probably want to add all of that Kubernetes functionality at some point anyway - eg you may just at first deploy your server/app via ClickOps, have some issue, decide GitOps is the way to go, then decide that you really need to have automatic certs, then decide that DB backups would be good to have. With Kubernetes you just keep extending it and never really have to "rethink" the approach cos it's really difficult to shoot yourself in the foot unless you really want to and have a shred of understanding (and to clarify I'm speaking about small deployments), and of course because you're using it yourself your knowledge grows meaning that your expertise grows.