For sure. My first desktop computer was a pre-built and a couple years later I changed the graphics card myself but it didn’t have much modularity beyond that and ram because of the power supply and motherboard. My second computer I paid somebody that I knew to assembly it for me, but there are websites online that provide this service as well for an extra fee. That ship of Theseus computer is still running with only the case, motherboard, and power supply being original.

There are youtube tutorials that walk you through the whole process of building a PC, it’s essentially like legos so it’s pretty straight forward if you follow along. Connectors are shaped to only go a certain way, components like ram and the cpu are asymmetrical with notches to aid placement, and things like where usb headers and power connectors go is straight forward as well.

And hell, my next “desktop” will probably just be a steam deck with a dock depending on how the next version looks compared to my aging desktop. Tons of options out there!