I've been a solo Web/Internet entrepreneur for most of 20+ years, non-stop.
The DevOps side of things is trivial in the beginning and takes very little time compared to actual development.
Ubuntu server, Nginx, Mysql or Postgres, PHP, Go, Redis. Configured reasonably, it's a ridiculously reliable stack where things very rarely go wrong.
I prefer DigitalOcean these days. Takes And that's it. Back-ups on eg a database focused droplet are automated by DigitalOcean. Occasionally I have specialized back-up needs, and I'll do a bit of custom work for that. Most of this could be offloaded by using DigitalOcean's database service, I just prefer to limit cost by not.
Under no circumstances would I use Kubernetes for a smaller to medium size service.