Middle sized company server architecture

I am designing server for middle sized company which should offer services as accountancy software, property record software, file server etc. My idea is using Hyper V server as type 1 hypervisor. As virtual OSes I need use Windows for one of the requested software (company has the license). For other software I am thinking about 1 virtual OS for 1 application + virtual server dedicated for database which would serve for all virtual OSes + virtual OS for file server. I am attaching an outline.

outline

Is this a sane idea? Should I consider Kubernetes as a platform for my apps? Thanks for ideas.

Yes, separating applications is standard practice. Limiting the number of things installed on any one instance is easier to maintain, and better security isolation.

Sure you could implement with VMs on Hyper-V, that is an option for compute platform.

Ask the organization to define what the recovery time objective should be. On a single server, if hardware failure took it down, all the applications would be down until it was replaced. Fixing it faster than a day may require same day service contracts, or multiple VM hosts in a highly available cluster. And test your backup restores.

Licensing is more complicated than having one single license. Ask a licensing person at your reseller to verify.

Containers, and especially Kubernetes, adds a quite different interface to compute. New concepts of container workloads, services, networking, and deployment methods. Something to explore, but applications would need to be adjusted to make use of the APIs. Do research and a proof of concept with your applications first before committing to containers.