For the 'sandbox' - it's really only a technical way for Luxee to present the encounters. He said, that the way he thinks/works, he feels like he has to show everything without time jumps if he is doing the game VN style. So this is him coping with only showing the interesting encounters without filler. This has problems right now as there seem to be no requirements between different event paths where there should be some - as well as missing time requirements of when events get playable, even made more complicated with some of them not being in the 'retail' version.
From a technical point, you have to click/activate encounters you don't want to see, so the game can progress for Luxee just jumps over that content instead of coding separate branches. So content you click but don't see is non-existent in your universe, not just not shown but happening off-screen.
Can't tell you anything about what exact paths/groups of LIs there will be in the end. But would assume something similar to PL with a harem and several different group endings. Not sure which characters would actually qualify for their own special ending with the current state of the story and differing setup from PL.
Edit:
Just saw I missed the last couple posts before replying. Ignore the stuff you already know about.