For example, I've been thinking about delivering boring and old tech based on HTTP -- such as Wordpress, Discourse, NodeBB, Directus...but in cloud-native Kubernetes with full managed end-to-end lifecycle management, including HA, snapshots/backups, ingress setup, object storage and persistent volume, disastrous recovery, Grafana dashboard, etc. All you need is select an app and provision it and wait for 5-10 minutes to get your service out. You don't get to deploy your own stuff yet, say like Docker at the moment, but that could be done with virtual clusters in future.
This is effectively the same as DOKS one-click apps, but slightly better because you don't have to manage infrastructure (we, or as of right now, I do, theoretically speaking), but I'm also sure somewhere someone else just did what I did better. It's more like a traditional PaaS (say like Heroku and fly.io) but having some SaaS elements (cloud offerings) as well.
So, how do you validate the feasibility and justify for this product idea, and how do you find more competitors that already done what you do so that you don't reinvent the wheels?