I mean the stuff is probably archived somewhere online and possibly already ready to just download or run but that’s no fun and I am also curious.

If you like a challenge you could try to write your own crack. At some point in the installer's code there must be a condition that goes "If entered serial is correct, jump to installation, otherwise jump to error message.". On x86 machines a "jump if" is represented by the byte 0x74, whereas "jump if not" is 0x75. In the most simple scenario all you need to do is find the exact byte representing that jump and replace it with its opposite. The installer will then let you proceed if you enter any invalid serial.

At minimum you'd need a disassembler (ideally one that lets you run the installer in some kind of debug mode), and a hex editor. Be warned that my knowledge was very limited back then and has likely deteriorated even more since. Also it can quickly get much more complicated if the installer comes with any form of tamper protection or obfuscation.