I am a developer and want to have my own server at home to install Windows Server and Linux. While I have some experience with using/setting up Linux as server I have 0 with Windows Server and my workplace is working strictly with Windows Server. While deploying things is not my responsibility still I want to learn this stuff. I want to be able to use Windows Server with azure devops (on premises) to build CI/CD pipelines. Host my own git server, test applications for stability etc.

The machine needs to use low power since I am planning to run it 7/24. I must be able to able to upgrade its cpu, ram and disk over time. What system specs would you recommend? I got my eyes on the Beelink S12 Mini but it has single channel ram and supports up to 16 gb or should I go with something like Asrock Deskmini X300 and buy second hand cpu, ram to make it cost lower?

I am open to suggestions. Thank you.

EDIT: Budget is around ~250 USD