We are building a solution from scratch to involve VM4 with J4 or J5 selling digital products but we do have a plan in near future to make app on mobile to interface VM4 and place order directly through the app.
is there any straight forward solution for this? and how to get started.
The core VirtueMart does not have a REST API, which is necessary for developing a mobile app. However, Joomla 4 and 5 support REST API. Therefore, you will need to create a "webservices" plugin to establish a REST API for VirtueMart. Once this is done, you can easily proceed with building a mobile app.