Hi,
Stefan from the QEMU project has written a nice blog post on out-of-process emulation (i.e. doing things outside of QEMU in this case). It's a bit of a brain dump but useful for understanding some of the issues associated with device emulation.
It doesn't cover our proposed isolation ideas but is a good primer non the less.
http://blog.vmsplice.net/2020/10/requirements-for-out-of-process-device.html