Some temporary thing would be fine enough, when it comes to the sweeping, imo.
With regards to that, and the indication on what’s available, I think you can just expand a bit on the [WIP] tags you already have in place. Since there’s a lot of them, it’s a bit murky when it comes to the level of implementation they have. Splitting them in [WIP] and [Coming Soon] or something along those lines would already indicate what places HAVE some content already and which don’t.
For the questlines, a “This is as far as you can go in this version” final placeholder event works wonders. I hit those in some other projects I follow and they’re always reassuring. You could also take a similar approach to some other elements… take, for instance, the Rituals with the maids:
From the content we already have with Az’ea, I’d assume the idea moving forward is to have more options for the maids as well. In which case, say, Delia, could have a list of options that looks like:
[Footjob - 0 obedience] [???? - ???] [Not implemented]
For, respectively, an action that’s already open, one that can be unlocked, and a placeholder that indicates there is more content planned for that character. Looking at something like that would already tell me a lot about whether there’s more content in the current version or not.
For regular main quest stuff, just have a special “You have reached the end of main content for this version” special day event that pops up at the appropriate time. The player may want to keep playing for more side stuff, but that at least tells them they’ll be done with the main as well.
Finally, if you’re keeping track of the version differences and adding more content on later days, you can always have, during development, a cheat menu that expands on the current “start at first day of content for this version”. something like:
day 10 (version 0.4)
day 15 (version 0.5)
etc…
Could be a hassle, could be chucked out of the window if you rework the early game, but if you expect that players won’t be able to keep carrying the one save, this can give them some help if they’re coming back after waiting out a couple versions or whatnot. This last suggestion COULD be more hassle than it’s woryh, as it’s really kind of a tiny thing.
Hope this helps shape up some of these ideas better