Way heavier weight, but it seems like the only realistic security layer on the horizon. VMs have it in their bones to be an isolation layer. Everything else has been trying to bolt security onto some fragile bones.
You can write completely secure code and run it in a locked down VM and it won't protect you from lethal trifecta attacks - these attacks work against systems with no bugs, that's the nature of the attack.
Sure, but if you set yourself up so a locked down VM has access to all three legs - that is going against the intention of Qubes. Qubes ideal is to have isolated VMs per "purpose" (defined by whatever granularity you require): one for nothing but banking, one just for email client, another for general web browsing, one for a password vault, etc. The more exposure to untrusted content (eg web browsing) the more locked down and limited data access it should have. Most Qubes/applications should not have any access to your private files so they have nothing to leak.
Then again, all theoretical on my part. I keep messing around with Qubes, but not enough to make it my daily driver.
