I would say nl10 to nl100 regular! in 6 months is not realistic; however have shots at nl100 is possible, but that means you are nl50 player at that time.

Either way good luck, if you want to get through all this - run in your head(visualize) 2-3 nightmare scenarios and what you will do :
1) you have time for poker or you fall out from your plan (or completely fucked up weekly schedule and played like 3-5 hours and studied even less)
2) you busted your roll/extreme downswing
3)burn out/no motivation anymore

It is about talent/personal qualities as well, in my career Ive stuck at nl50 for years, nl200 for years. Clearly I have not the best poker talents

It really is not the best idea to set a fixed time goal. It's good to have goals, but poker is not as scheduling a training plan.

First and foremost, what's the "precondition" of being "regular on a stake"? Is the bankroll the determining factor, i.e. start with $400 on NL10 (40 buy-ins) and work up yourself to $7.5k in six months to regular play NL100 (with 75 buy-ins)? One could easily excel what that meant in terms of winrates and volumes and stuff. Assuming a start bankroll of $400, a constant winrate of 3bb/100 on any stake, an immediate switch of the stake once the treshold for the next stake is reached and 40 hrs / week for plaing (rest for study), it would take round about 750k hands or 4 months to reach NL100 with 75 buy-ins (assuming no deadly downswings will happen). So it's "doable", but realistically, it will take much longer, likely even longer than 6 months.

Or is the skill the determining factor? I would say that NL100 is not that much different from NL10, if one "knows" what he does. Reason is that Zoom is pretty regheavy on any stakes, fish are not uniform, so it's difficult to really outplay them (because everybody has different leaks) and - first and foremost - rake is brutally high on the low stakes, which means that our winrate has to be significantly higher to win post-rake.

That said, yeah, with strong, disciplined work, a calm mindset (no tilt!!) and a clear plan of what to study (and not blindly investing hours by hours to click around with a solver), it is "doable" - but challenging. Granting yourself some buffer, i.e. not jumping out of the window if it takes longer (up to a year) is likely better.

WARNING: In any case you should not bind yourself or your life (plans) to that idea!! Have a fallback plan to not sitting there w/ empty hands if you fail. Quitting your day-job to immediately start a 60-hour-poker-career simply is a stupid plan. Last but not least because it sounds funny at first but you have no clue what it means to play / study 60 hours weekly, week after week.