Just use Plaid
There are two banks that I would like to connect that sadly don't have options for Wallet, such as TD Bank, and some options just won't connect (Fidelity Investments). These banks do allow for third party integrations, but they are usually through Plaid, which is a fintech solutions company. These are banks that have millions of customers (43 million for Fidelity, 27 million for TD), not local credit unions, both of them lack proper budgeting apps (TD MySpend only works in Canada), and both should reasonably be supported by most fintech apps.
I understand that Fidelity recently made some changes, requiring apps to switch to their new API, and I understand that the developers of this app are already working on numerous new features while maintaining stability. So why not take some work off their plate, and use Plaid to integrate with almost every decently-sized consumer bank? You only have to worry about one API instead of dozens, you open up your potential market to many more people, and you can potentially save money depending on how much time you spend maintaining those API's.