Yes, Jazz Cash can be added to Shopify as a Private payment gateway. it will work exactly same as other payment gateways listed on Shopify.
Send me a DM for more details.
Hi, if you have still issue on jazzcash payment gateway integration.
Jazzcash provide Hosted Payment Checkout. and Hosted Payment Checkout is support by Shopify.
you can also visit my channel to get the new video with code on jazzcash payment gateway.
also take a look on my code at bitbucket.