Is it Islamically permissible to obligate a poor person, to whom we have donated for a charitable project, to pay a fixed monthly percentage to be donated to other projects?

Assisting the poor by establishing projects for them takes various forms. However, obligating a poor person to pay a fixed monthly percentage to donate to other projects transforms the transaction from charity to an exchange, and exchange contracts are not valid with an unknown consideration. Among the proposed legitimate solutions is to lend the poor person the cost of their project and facilitate repayment, so that they can earn profit and repay the debt simultaneously. Then, the debt installments are taken and given to another poor person in the same manner. Furthermore, each beneficiary among the poor, after their project succeeds and their debt is repaid, should be asked to contribute to this project as a donation, not an obligation.