As a merchant accepting Payconiq transactions, what are the technical requirements for my customers to be able to use Payconiq by Bancontact?

None. You do not need a payment terminal or any other technical equipment to accept payments made with Payconiq carried out by your customers- using the Payconiq by Bancontact app by scanning a QR code or sending payments to you via the 'Shops' button. You can log into the merchant portal from any web browser.