There are Linux-based (either Debian, SUSE or, of course, Red Hat) desktop virtualization solutions which are fully Open Source. Any modern version of a Linux distribution incorporates support for KVM, so if your hardware allows it, it turns the operating system into a hypervisor platform. On this basis we install oVirt, which will be responsible for transforming the Linux into a node of our virtualization system.
Finally, we will need a virtual desktop management platform as UDS Enterprise, which has a fully Open Source version and, in the same way as Red Hat, there is the possibility of hiring support, updates, patches and maintenance.
UDS Enterprise is a multiplatform connection broker for Windows and Linux virtual desktops administration and deployment. It enables the management of user access to IT resources in the Data Center or Cloud and the consolidation of user services by means of new or existing modules. It supports Open Source hypervisors, authenticators such as OpenLDAP and different connection protocols (RDP, RGS, XRDP, NX, Spice…).
Using Linux, KVM, oVirt and UDS Enterprise you can leave aside proprietary systems, since all of them are Open Source software. In this way, we will obtain a 100% Open Source VDI platform.