App sizing considerations and comparison between Qlik Sense Business (QSB) and Qlik Sense Enterprise SaaS (QSESaaS) features, as well as QlikView and Qlik Sense comparisons can be found under the following links:
Below are a few App migration paths to Qlik's SaaS editions:
I. QlikView Server migrating Apps to a SaaS edition of Qlik Sense:
Once a the SaaS tenant has been deployed, Qlik Sense Desktop can be installed on a Client computer and authenticated against the SaaS deployment chosen. This allows for the first two conversion options below of the QlikView document to a Qlik Sense App. See How to authenticate Qlik Sense Desktop against SaaS editions
QlikView Documents can also be directly uploaded via the Cloud Hub, where they automatically get converted into a QlikView app (.qvapp). With this format the QlikView Visualization Objects are preserved, but the App cannot be further developed/changed, or converted back to QlikView document. Steps are available under Uploading and sharing a QlikView app in the Qlik Sense cloud hub.
II. Qlik Sense on-premises migrating Apps to a SaaS edition of Qlik Sense:
Migration of on-premises Apps to SaaS can be done by manually exporting them via QMC and then importing them directly via the tenant's Cloud Hub's interface.
It is also possible to distribute QlikView documents (or Links to documents) and Qlik Sense Apps directly from the on-premises Qlik site to Qlik Sense Enterprise SaaS (QSESaaS) for consumption using the Cloud Hub.
Qlik DataTransfer allows for data to be automatically uploaded from on-premises to your SaaS edition of Qlik Sense. This allows for the environments synchronize App data and data sources. (not the App itself as it is done with Multi-Cloud deployments)