Scaleway came up but is more expensive. IONOS did not come up in our research.
Part of what we tried to do was to make ourselves independent from traditional cloud services and be really good at doing stuff on a VPS. Once you start doing that, you can actually allow yourself to look more at uptimes and at costs. Also, since we wanted everything to be fully automated, Terraform support was important for us, and OVHcloud and Hetzner had that.
I'm sure there's many great cloud providers out in Europe, but it's hard to vet them to understand if they can meet demand and if they are financially stable. We would want not to keep switching cloud providers. So picking two of the major ones seemed like a safe choice.