DEC Keyboard LK401 has serial interface, 4800 Baud, 8N1. See more information on the keyboard hardware here. The keyboard is solid and heavy, has superb tactile keys and is of the old 80ies quality. That you simply cannot order on Amazon or so. For a long time, the keyboard was supported by the Linux kernel, but this time is gone. My idea: connect the keyboard to a microcontroller that can connect to a PC via USB.
Hardware The Arduino MKR Vidor 4000 is a small but powerful device with Arduino compatible connectors and libraries that makes it possible to program it by using standard Arduino IDE. The Arduino MKR Vidor is packed with amazing functions. This small device contains: Control Unit is a Cortex-M0 32-bit SAMD21 microprocessor, running at 48Mhz, 256KB Flash, 32KB SRAM 2MB Flash ROM, 8 MB SDRAM Intel Cyclone 10 10CL016 FPGA, with 16K logical elements, 504kb of embedded RAM Bluetooth (u-blox NINA-W102) WiFi (u-blox NINA-W102) USB Camera Interface Micro HDMI Output I2C connector LiPo Connector Mini PCI Express ATECC508 crypto chip https://docs.