If you never heard of Raspup before, let me tell you that it’s a Debian-based GNU/Linux distribution built from the Woof-CE build system that was originally developed by Barry Kauler, the creator of Puppy Linux, and binary compatible with Raspbian (the official Raspberry Pi OS).
As such, Raspup is a Puppy Linux port for Raspberry Pi. Raspup was created by Michael Amadio and it’s designed to run on ARMv7l hardware, specifically on the Raspberry Pi Zero, Raspberry Pi 1, Raspberry Pi 2, Raspberry Pi 3, Raspberry Pi 3+, and Raspberry Pi 4 single-board computers (SBCs).