if that’s even possible
Nested virtualization is possible with supported software AND hardware, a lot of consumer products lack the hardware to make it happen though and even then still inefficient. I've tried in the past and I get an error plainly stating I can't run hypervisors within a hypervisor. The concept has been around for a while especially with large corporations like VMware and IBM.
it has a significant learning curve last time I checked
It's a learning curve but if you can manage virtualbox it shouldn't be too hard to figure out Qube manager. The latest 4.1 release is definitely the best one thus far for stability and ease of use since the automatically updater actually works!
The Tor implementation on Brave is not for serious use cases and I would only use it for general things.
Additionally you can use regular firefox to view onions with a few simple steps try googling it. Once again this wouldn't be for serious use cases and you lose all the protections Tor browser provides.