Security is a rabbit hole.

You’re going to end up wasting a lot of time and effort on learning about something that in the end will not have a substantial impact on your computing experience.

It will make you look good in front of losers on the internet you’ll never meet, though.

Try searching for dell optiplexes on ebay and see if any of them suit your needs for a better price.

If you don’t need something with a small form, then don’t get it. You end up paying more for less.

Oh god, don’t waste your money on a mini PC unless you specifically have a reason to get something small.

You’re literally paying more for worse hardware because of the form factor.

Instead, try getting a used Dell Optiplex. You can buy them at walmart for under $100.

Also, don’t kid yourself into thinking your server is going to be more popular than it is. If it’s just for you, then there’s no way you’re going to exhaust its resources unless you’re specifically trying to.