V-USB with ATtiny45 / ATtiny85 without a crystal | Code and Life
Pololu USB AVR Programmer v2.1
GitHub - obdev/v-usb: A Firmware-Only USB implementation for Atmel's AVR Microcontrollers
Amazon.com: Geekstory for ATMEL 51 AVR USB ISP ASP Microcontroller Programmer Downloader with Cable + 10Pin to 6Pin Adapter Board for Ender 3 or Ender 3 Pro : Electronics
work in progress » V-USB tutorial (software-only usb for mega & tiny)
V-USB - A Firmware-Only USB Driver for Atmel AVR Microcontrollers
Amazon.com: HiLetgo 51 AVR ATMEGA8 Programmer USBasp USB ISP 10 Pin USB Programmer 3.3V/5V with Cable : Electronics