The Nebula CA we built at Slack was very specific to Slack's internal devops, and just wasn't generalizable. It is highly automated there, and is custom tooling, just as you describe. The open source version is somewhat bare bones (a command line tool for CA vs something like vault).

I will say that the OSS tooling of Nebula is everything someone needs to stand up an entire working network on every common platform (linux/mac/windows/ios/android), but there is a definite gap in simplification that we need to address to make it easier for smaller scale use cases.

We actually have a managed enterprise Nebula offering at my current gig, but that's rather a different market than Tailscale, so I'm avoiding talking as that company as opposed to a Nebula OSS project lead. The commercial offering is targeted at large enterprises, because that's the market where Nebula has unique advantages. It also means we don't currently have a freemium or smb type offering, and are not prioritizing creating one at all. I don't want to give people false hope that we will, and would prefer to see the OSS project improve to address the small-medium use cases.