One of the fundamental challenges in migrating SAP ECC to S/4 HANA is the lack of knowledge on the plethora of customizations done on legacy SAP ECC.
To address this challenge, there are two leading products in the market - ServiceNow Gekkobrain and Celonis.
Gekkobrain helps teams in getting a deeper understanding of custom code that was developed to extend the functionality of SAP. It analyses the custom code base and identifies relevant HANA issues and also try to fix the issue.
Gekkobrain flows is a component that uses ML to understand and visualize the business process. It can understand main flows, sub flows and deviations and help in identifying automation opportunities. This capability of Gekkobrain flows is also branded as a Process Mining Tool.
ServiceNow acquired Gekkobrain to integrate it with the NOW platform and leverage its workflow engine to automate workflows for customized SAP code (during HANA migrations).
Another popular tool that is used for during SAP modernization is the popular process mining tool called as Celonis. Celonis is used for retrieving, visualizing and analyzing business processes from transactional data stored by the SAP ERP systems.