I'm confused by your wording.
Are you trying to build a new fintech product that will have zero connection to these banks? Or, are you trying to build a product that interfaces with these banks by trying to piggy-back off of their own APIs?
Are you trying to build a new fintech product that will have zero connection to these banks? Or, are you trying to build a product that interfaces with these banks by trying to piggy-back off of their own APIs?
To be clear - we provide this interface with the banks as a service to other companies who want to use the consumer's data inside the bank account (with their consent of course). A good example is a loan affordability calculation. Instead of asking a user to upload a bank statement, we provide the interface with their online banking profile which allows them to extract raw transaction data more quickly. We then send that data to the company is offering the loan so that they can make an affordability decision.
In our country there are other companies who do the RE method. I am not aware there is another way, other than scraping and that because our banks don't offer external API's.
If you're looking to RE these mobile apps solely for inspiration, you're better off hiring senior-level employees with experience working for banks and/or in fintech and starting from there. If you insist on RE-ing something, then try to RE a fintech product that you are trying to emulate.
Alternatively, if you're telling me that you guys plan on somehow piggy-backing off of the banks' APIs, then you need to work directly with the banks. If that's not an option, then your product has already failed and it's time to move on.