Oh my god, OSX Server is still a thing (genuine surprise)? I suppose it depends on use case, but I gave Server an honest attempt once, and eventually scuttled the entire thing; I'd love to try an Enterprise ready MDM from Apple, OSX Server isn't it. Very similar features that one would come to expect, but there's not much depth to them when your service demand begins to scale.
So one thing I discovered by reading this article: Server.app seems to be available to anyone with a Dev account, even an old free account without a new paid subscription.
Curious to hear your thoughts, especially with regards to step 3 - this is not my home soil at all. Thanks!