Out of interest, why not just PXE boot prebuilt images (buildroot/etc) that run from memory as your OS? That would save you the hassle of maintaining a stateful server, installing an OS, ensuring configuration is up to date, etc.
In this case, you’re assuming a huge number of things like infrastructure and other requirements are in place, and all of those things take a lot of time and work, if they’re even appropriate at all.
But even if that's the case , couldn't they use something like vram if they are running out of memory of are we back to square one?
We run a thin base OS on the boxes and then VMs on top which we consider more ephemeral. The frequency of needing to update that base OS is v. low.
I think there's a case for building a custom PXE booted RAMdisk image to replace the install though; something like what Equinix Metal (formerly Packet) do with Tinkerbell (https://github.com/tinkerbell); they call it an OS Install Environment, but the idea is a small lightweight linux install agent that can DD a golden image onto the disk (vs. an install each time).