First and foremost, let's jettison the terms "emancipation" and especially "minors". The former has historical connotations related to slavery, while the latter is an ageist slur that implies that young people below some arbitrary age are somehow less important than those above that age limit, as even Hillary Clinton famously pointed out in the 1990s. Replace the former with "release (of restrictions)" and the latter with "youth" or "underage". For the same reasons, the terms "access" and "custody" have already been largely replaced by "contact" and "residence", respectively, in most of the Anglosphere.
Secondly, we need to follow "Alberta rules" and set the default age of majority (legal adulthood) at no higher than 18, and NO age limit for anything can be set even a day higher than 18, except with truly extraordinary justification (like for being President or VP of a country with hair-triggered nuclear weapons and other WMDs), or for senior citizen stuff. And for any (non-convicted) individuals over 18 to have even one iota of their civil rights abridged or taken away even temporarily, the onus is inherently on the state to prove that the individual is incompetent, NOT on the individual to prove their own competence. Anything else is inherently ageist, classist, racist (by extension of and intersection with classism), and/or ableist in practice, if not also in theory as well.
Thirdly, while for young people below the default age of majority, the onus would by definition be on them as individuals to prove their own competence, it needs to be done in a fair and just manner and as objectively as possible. And doing so needs to also provide at least some sort of alternatives to the traditional and narrow (and increasingly outmoded) milestones of adulthood for generations past.
Twenty-One Debunked's early thought is to have two categories of release: 1) "conditional release", which begins the process, and can still be revoked if the conditions are not met, and 2) "final release", which will happen after a year or two following conditional release, or age 18, whichever occurs sooner, and cannot be revoked. The minimum requirement to achieve conditional release should be 1) the completion of Tanner Stage 5 of puberty plus a mental age of 16 or higher as measured by any standardized IQ test, college entrance exam, or graduation exit exam, OR 2) a chronological age of 16, whichever occurs sooner. The minimum age to achieve final release should be a chronological age of 16 or at least one year since conditional release began, whichever occurs later. All of the other details are of course not cut-and-dried, and should be flexible. (And unlike Dr. Robert Epstein's paradigm, let's NOT follow the DMV model! Only the most left-brained, out of touch, ivory-tower academic elites could think that is somehow a good or wise idea, because reasons.)
And when Universal Basic Income (UBI) is eventually implemented, only upon final release (or 18, whichever is sooner) should an individual receive their own unconditional UBI directly. Rather, upon conditional release, they should receive a "conditional stipend" instead. (Before any kind of release, by default their share of UBI would go directly to the young person's primary parent or guardian.)
Of course, for as long as we live in "mass society", for all of its myriad flaws, there probably still should be some sort of hard age limits (i.e. purchase ages for alcohol and other psychoactive substances, age of consent, working in truly and inherently dangerous jobs, etc.) that remain true regardless of one's individual status, but nearly all age limits can be at least partially replaced in that regard. And again, no such age limits should ever be higher than 18.
So what are we waiting for?
