Have you read HN's most famous comment about Dropbox? Do you know why it's famous?
I'm not that familiar with any of these, but SmartOS sounded cool when I looked it up.
My point on the other hand is that all that flapping in the fly.io article is too complex and completely unnecessary because that problem can be solved with a better, simpler solution which has existed far longer.
Which means we support what people already use. Postgres is great but I wouldn't choose to run it for fun. Our customers use Postgres. Node is not my favorite runtime, but we have good support for Node because it's popular. Devs are willing to package their apps as docker images. So we run Docker images.
Your better, simpler solution would cause our company to fail. I'm very familiar with Joyent and SmartOS. They lost the container battle, despite the elegance.
Docker's days are numbered: too many scandals, Google gave up on it. It is only a function f(t) before it goes out of fashion, just like everything else in IT.
Post scriptum: why persist on the illumos-zones-ZFS-configuration management with OS packaging constellation? Because it is bullet proof not for months or years, but decades thereafter. It is good business: less maintenance investment means more profit long term, and in business, it is the long game, and not trend pandering which counts. No business survived on trend pandering, for reasons which should be quite obvious.
You already unpack Docker, and when I read what all you had to do it was obvious to me that what you are doing is far more expensive than if you had gone the SmartOS-lx branded zone-ZFS route; you could have chosen to do so with the bullet proof substrate that are the lx-brnaded zones, the illumos kernel, and ZFS. The customer in your model is none the wiser anyway but you did not do so, which is illogical, since you take it all apart and custom-deploy it on custom infrastructure anyway. The system engineering and maintenance costs will kill your business long term, not to mention what they will do to each and every one working on that in terms of health and personal life. Babysitting computers and software will never be a profitable position.