Is there a Dan route planned? Judging by the achievements, there seems to be but I am guessing it's not implemented?
Viewing post in February 2021 Update: The Alpha is Here! comments
The current routes are Malik, Chris, and Nate/Jake (as a pair). There's a fourth secret route technically in the game but that may not be obtainable yet.
In general, if you want to help test right now (thank you!), it'd mostly be useful to find obvious errors (sprites missing faces, missing clothing, actual game crashes and errors, typos in text).
The actual obtainability of things (and how routes and actions link together) may be changing as new scenes and routes are added, so I'm not concerned about them at this point in time... that's really what the beta will be for testing. (For example, if you can't obtain the end-game bonus for maxing out James' friendship currently, that's fine, because more scenes in the future may let you do so.)
I've been trying to get Nate alone.
The only thing I've seen that is problematic is that in several areas the shading of people's hands seems weird. I'll try to send screenshots in the page you've indicated.
Only seen some obvious WIP disclosures near the end.
Had a few errors but . . . I'm a dirty cheater so it might be me messing with scores.
I do find happiness to be fairly restrictive.