You can run kubernetes on mainframes. They’re not as old/out of touch that most people think
https://www.ibm.com/docs/en/zos-hot-topics?topic=new-kuberne...
As a rule of thumb, if there's something in computing you've heard about, expect IBM to also have heard about it and made something like it for their machines. Sometimes they lag a bit but eventually they converge towards having their own of all things computational.
I didn’t know this either until I started just researching a while back. It’s amazing. They get a bad rep, but they are very very awesome and modern.