I have all my personal data in its own isolated VM (Qube). I do all my browsing in another VM, which has its own home folder and no access to my personal VM. All my sensitive stuff like banking is done in its own VM. Every proprietary application gets its own VM (mainly Teamviewer and VS Code).
So if I do happen to run some program that's malicious, it has effectively zero access to anything sensitive unless it's aware of Qubes and knows how to break out of the hypervisor (non-trivial).
It's really not easy to get a code signing certificate fraudulently (or to steal someone else's), but of course, there are some issues with code signing: for example, certificates are relatively expensive, so very few OSS/free software projects sign binaries.
And there are the modern applications from the Microsoft Store or self-distributed as msix/appx which are properly sandboxed.
Windows 10X original roadmap was to merge both sandbox models, and it is also part of Project Reunion goals.
I use it for specific purposes like possibly hostile browsing environments but I'd never consider it for a mainstream system to work on.