Is this approach not just Capistrano but using containers and specific to python? You could just use firecracker microVMs and ansistrano to implement this same workflow but get better isolation from firecracker.
Firecracker is definitely very interesting. Would require more ops work for us to run bare metal EC2 (we currently use Fargate). IIUC reusing pre-existing environments would require us to share ext4 filesystems across the VMs. Not sure if antistrano helps here but will look into it.