There are people that use LXD (LXC containers managed by the LXD hypervisor) on embedded systems.
I think it gives the best performance / easy of use. Since you have a very specific use-case, you can customize quite a bit.
Some things to note:
1. When installing LXD, you select the
storage backend, which is the location to store the container files.
The simplest storage backend is
dir, which means that it does not use some special filesystem (like ZFS or btrfs).
Because your use-case is very specific, you might be OK with
dir. A disadvantage of
dir is that the creation of a container can be slow; you would not mind because you create just a single container.
2. LXD works best if your Linux kernel has proper AppArmor support. If you can select Ubuntu for the host, it would be the easiest choice.
The alternative is to use LXD as
a snap package. See at
https://docs.snapcraft.io/core/install on how to install the snap package mananger, then install LXD by running
snap install lxd.