Is zakat obligatory on a meager income from teaching, rented room income, a non-interest-bearing dollar bank account, the capital of financial sukuk that generate small monthly profits, and the savings balance in the bank account?

Zakat is obligatory on money if it reaches the nisab (threshold) and a full year (hawl) passes over it, whether it is saved at home or in banks. As for real estate prepared for rent, there is no zakat on the property itself. Rather, zakat is due on its rent if a full year passes over it and it reaches the nisab, but if the rent is spent, there is no zakat on it. Money earned from teaching is not subject to zakat unless a portion of it is saved and a year passes over it. Regarding sukuk (Islamic bonds), if they are held to benefit from their profits and not for trading, then zakat is due on the saved profits after a full year passes. And know that zakat does not diminish wealth; rather, it increases it in blessing.