If you enjoy researching, tinkering and customizing everything exactly how you envision it then build a custom one. If you "just" want to use the thing and run some docker containers then buy a NAS. From what you wrote I think a NAS is what you are looking for, especially the low maintenance part. Just make sure it's not the most basic one, so it actually has the power to run what you need.
The one great thing about Synology NAS is that most things are right there in the UI or package center. You can just install them without researching 100 different alternatives, and configure them in the UI instead of config files. What's not there can be installed just like on a custom server, because it is just a regular server after all. You also get good customer support if something doesn't work, especially useful when you're not as knowledgeable in everything yet.
You can also selfhost it and get the premium features for free.