If I become a US resident and a non resident of Canada and have Canadian sourced income, how would this income be taxed? Will it be subject to 25% withholding on net income, or be just subject to federal income taxes? What about provincial income taxes? (I understand GST/HST is required on these sales.)

Im a sole-prop earning self employment income in Canada. I have my products stored by a third party in their Canadian warehouses and when sold and they ship to Canadian customers in Canada for me. I have no other “presence” in Canada then my products stored in a third party warehouse (Amazon FBA).