You can only take retro so far, especially when it comes to computers. Older hardware won’t get you far if you need something actually usable. The most you can do is to make, usually 3D print, an old-school shell around new hardware. The more hardcore, however, will force those new parts into an original shell. That’s exactly what Reddit user Tylinol did with SErEndIPITy, a more or less recent PC gaming rig shoehorned into a 386 case, with some modern amenities like a CPU temperature display.