I use Alpine Linux for all my dockers, small and fast.

2.5" disks are SMR, you don’t want that in a raid.

Unless you have use case for that much horsepower I would suggest, like others here, buy a mini PC as a start and if you need more down the line buy a second one. They are cheap, fairly quiet and don’t use much power.

Looks like a pinecone to me 😀