Is there is no walkthrough mod for this
You don't really need one rn, Most of the choices are either super obvious or have immediate effects you can see
Jacq has confirmed picking Isabella for the experiment will eventually have a payoff, but not exactly what that payoff will be.Agreed. The only choice I can think of so far that has noticeable effects later down the line is who to have Isabella create for that experiment, the movie star or herself. If you choose the movie star you get a pretty good scene later on while choosing Isabella has no payoff yet. Though it probably will lead to something else eventually I'd guess.
The only other major branching I can think of for now is whether or not you decline Moonsong the first time (but this merges back together around Ch 5 and only is minor dialogue differences after that) and which path to take for Lucia (normal or manipulate). So far, the Lucia choice is mostly scene variations, but according to dev logs Ch 8 should have a big character growth payoff for people on the 'normal' path with her. And Jacq has said there will be more branching as the story continues, so eventually a WT might be useful. But there's no 'love points' or anything like that you need to manage.
You can definitely do this, but it's actually several variables you need to change if you want to swap paths properly.Nothing that the good "old" URM won't solve by changing a variable if need to make a split save playthrough in the case of lazy people like me that don't want to load an older save just to make a different path on that choice.