Hopefully, most young people who are alternatively schooled, homeschooled, or unschooled know that a high school degree is largely worthless. No reputable college or university in the United States requires a high school degree. However, all colleges will want to see a transcript, and this is one area of several where non-traditionally schooled applicants have a sizeable advantage. The time and effort that typical high school students put into their transcripts usually end with a verification that they are hitting all graduation requirements (e.g., 4 math credits, 4 science credits, 4 ELA credits) and a quick calculation to determine which honors and AP classes they should take to boost their GPA relative to their peers. But young people who are responsible for their educational pathways have the opportunity to walk admissions committees through a unique journey that was tailored to the applicant’s needs, goals, and interests. The best way to do this is to celebrate how the applicant spent their time engaged in deep, meaningful, and enduring learning experiences, without trying to conform it to a standard academic transcript (e.g., 4 math credits, 4 science credits, 4 ELA credits).
Additionally, letter grades or percentages are meaningless on a non-traditional transcript unless it shows anything less than a perfect GPA, which would hurt an applicant. Those who opt out of the traditional schooling system should never introduce the rank ordering aspects of grading that pull applicants down. 
Another benefit of opting out of traditional schooling is that young people get to avoid the relentless testing that is required in the classroom and for the state (e.g., Texas STAAR, New York Regents). Testing serves as a means for lazy politicians, bureaucrats, administrators, and teachers to assess and sort students, at the expense of students. Hopefully, the first time any young person takes a test is if they opt into it for their own benefit, such as taking the PSAT or an AP exam. However, one of the very few downsides to a non-traditional education is that many colleges will lean more heavily on standardized test scores during the admissions process. While the SAT or ACT most often serves as a disqualifier for top private colleges and universities (and as an automatic qualifier for many lower-ranked private or state schools), non-traditional applicants may have a more difficult time overcoming a poor SAT or ACT score than a traditionally schooled applicant who has a perfect GPA and ranks at the top of their class might.
The good news for non-traditional applicants is they should have ample time to prepare for the tests without being burdened by the unnecessary time requirements associated with traditional schooling (e.g., compulsory attendance, mandatory classes, homework, studying, testing). And for those who do not perform well on standardized tests even with plenty of prep, there are now.
It is worth noting that the most exclusive schools also require or “recommend” applicants submit SAT subject tests with their application. Non-traditional applicants should treat SAT subject tests as required if a school “recommends” them, and as recommended if a school “considers” them. Similar to the SAT and ACT, these tests can hurt an applicant’s prospects if the scores are low, but are unlikely to substantially help since so many applicants score in the high 700s or 800 on these tests.