Must one allocate a third of the profits to official charities that provide tax access, or is it permissible to give it directly to the needy, knowing that one's heart is disinclined to abandon unofficial needy individuals?

If the money to be spent is a donation from the donor and not obligatory Zakat, then there is no harm in spending it on any charitable cause. There is also no harm in registering payments with trustworthy official charitable centers for tax reduction purposes, and there is no harm if payments are limited to official associations. However, it is preferable to give directly to the needy to increase good deeds and act upon the Hadith: "Whoever relieves a Muslim of a worldly distress..."