With NetBSD's MICROVM kernel it's possible to boot in QEMU in around 10 milliseconds. Developers behind smolBSD took that and created a meta-OS and microVM generator to build tiny VM images that are fast booting and catering to your individual workloads/services. Ultimately you end up with ultra-fast, minimal, and reproducible micro-services from this smolBSD project.
smolBSD advertises on their project site at smolBSD.org that it's possible to build and boot your own customized BSD system in seconds. It's also possible to easily build Docker images from smolBSD too.
For those curious like I and wanting to learn more about smolBSD, it was presented yesterday at FOSDEM 2026 in Brussels. A video recording of the smolBSD presentation can be found at FOSDEM.org .