I my bank app I can check balance and history of 9 other bank accounts or CC - very useful for me.
I use Wallet (Badgetbaker) for android, and it is a very good budget and tracking featured packed app.
I can also recommend Outbank - using it on iOS as well as MacOS, including leading Bonus programs like Miles & More, PayBack and Amazon payments and much more in one app.
In Poland all top banks are letting for check your account ballance from other polish banks, transfer money via open banking (what is a bit confusing, because after this you have to login to your bank account), check credit history to be able to take new credit and some of them are letting confirm your personal information (BNP Paribas). Additionaly ING Bank is letting to analyse bugdet to show how much for what categories we spent.
It would be nice to have such options in Curve. Fintech Sync. was looking promising, but they are closing it for EU members. I think Curve should jump into this place ASAP to fill this hole.
What is important for me to ability to check balance (bugdet analysis would be great too) from accounts around the world. Polish banks are focusing now only on Polish accounts and Revolut, TransferWise, N26, bnc10, bunq accounts cannot be added there. I hope I will be able to see this soon in Curve.
Aggregator for pulling data for many German and Austrian banks accounts: https://www.finapi.io/