While IGST on import of services would be leviable under the IGST Act, the levy of the IGST on import of goods would be levied under the Customs Act, 1962 read with the Custom Tariff Act, 1975. Exemptions available to imports. Import of Goods under GST. GST on import of services.
The value of imported goods for the purpose of levying Integrated tax shall be assessable value plus customs duty levied and any other duty chargeable on the said goods under any law for the time being in force.

The value of the imported article for the purpose of levying cess shall be assessable value plus basic customs duty levied under the Act, and any sum chargeable on said goods under any law for the time being in force. The integrated tax paid shall not be added to the value for the purpose of calculating cess.

https://www.taxgyata.com/ap/imports-under-gst