Maybe the website makes it hard to find, but it is completely self hostable. Here is their GitHub: https://github.com/we-promise/sure

Providers that are in the app are: Lunch Flow, Plaid, SimpleFIN and Enable Banking

You can also import directly raw CSV and others

I had the same issue. Then I found https://sure.am/ . It has easy bank integration amongst others. Been using it for a bit now.

I have been using Authentik for several years now, works great with k8s. Not sure about the difference between Keycloak and Authentik tho (feature vise)