we are using similar setup and ended up using ansible for installing and setuping kubernetes cluster itself together with some other configurations like ipsec between the nodes etc. Learning curve for a new employee is small as every internal project is using the same directory structure and is completely gitops.
Actual services are then deployed to the kubernetes and it works great.
cryptocurrency maximalist would say that you are misunderstood that the Visa / MAstercart / whatever are fiat processors. Cryptocurrencies are currencies.
If you are interested in the boring part, so not how algorithms are invented and implemented, but more on the real world usage, I have written a blog "Commercial Cryptographic Key Management in 2018", where I am explaining a little bit about the hardware, people and processes behind it.
https://www.malgregator.com/key-management.html