Currently we need to do chained payment through Mobile android/ios Sdk which should also support Guest to pay i.e Credit or debit card payment.
We have integrated MPL (Mobile payment library) that supports chained payment but does not have guest payment as of now.
Also we have tried some other options like Mobile Express checkout but that is deprecated and does not support chained payment either.
Currently we have used the approach where we are hitting the REST call to get the Pay-Key referring to following url :
But the UI of the url is not user-friendly for live/production environment.