For those looking for one practical way to do this in the US, I can share my story.

In the US I waited until I was 24 years old to transfer to a 4 year university, because my parents were somewhat well off and utterly unwilling to help with my student loans when push came to shove - even though my financial aid was calculated based on their income and assets. At 24, I was reclassified as an "independent student", and my financial aid was now calculated solely on my (nonexistent) assets. The dynamic entirely flipped and I got to go full time, and even live in a dorm and stuff.

Between 18 and 24, then, one has roughly six years to get a 2 year community college degree out of the way for relative pennies on the dollar. That's a lot of time! Federal loans can pay for all or nearly all of this, but CCs are generally cheap enough that even on minimum wage one can generally budget the ~$100-200 per month it takes to take one or two classes per semester. (I wouldn't actually recommend paying out of pocket if you can avoid it, because your quality of life suffers far more from a $200 extra per month when you are making minimum wage vs when you are making six figures, but to each their own.)

If you fear you won't be able to transfer to a 4 year university for whatever reason, there are 2 year degrees which provide on-ramps to paid work; my original degree was going to be like that until I switched plans to the transfer approach.

The time I spent in a 4 year university weren't entirely covered by grants of course, but it was many multiples cheaper than it would have been had I insisted on going right out the gate. I don't think I would have been approved for the six figures of loans I would have needed with that plan with such unwilling parents. I walked away with low figures total in debt, which is much more manageable, and has a much higher ROI than e.g. $30,000 of a house mortgage. I actually somehow ended up holding less student debt than most college degree holders I have met here in Finland, where tuition is free and loans are intended to pay for everything else (housing, etc).