Testing on the desktops you claim to support isn't a relative question, it's an absolute question. You can do it - or at least an approximation of it that cover

Testing on the desktops you claim to support isn't a relative question, it's an absolute question. You can do it - or at least an approximation of it that covers the major facets like Xorg vs Wayland - with 25 employees, let alone 2500.