In many countries students at university are given a grant by the government. In other countries there are student loans.
Why not treat a ‘would be’ entrepreneur as a sort of student for three years. This would mean a grant or a special loan for three of four years. In that time the young person would be expected to set up the business.
To prevent abuse and claims by unsuitable people there would need to be some vetting procedure or preliminary test of the idea.
Edward de Bono