Can I hold/delay vendor payment until the product is shipped to customer? And release the payment after that?

You can have this functionality using any of the following marketplace payment add-ons. For receiving the payments, each vendor needs to save its account credentials in the marketplace account section and wait for the admin to click the 'Release Vendor Payment' button.

• PayPal Commerce Marketplace Add-on - Each vendor needs to save their PayPal account details in the marketplace account section and also give the app permission to the admin.
• Citrus Payment Marketplace Add-on - Here, the vendors need to save their bank details for receiving payments.
• MangoPay Payment Marketplace Add-on - Funds are escrowed in the MangoPay wallet and released after the validation period or can be released manually by the admin.
• Braintree Payment Marketplace Add-on - In this module, the vendors need to save their sub-merchant business account details and wait for the admin to release payment.

Please do contact us for any further queries or requirements. You can also check our Magento 2 Extensions for additional features