STM32 Bootloader: Programming STM32F103C8 via USB Port
USBTiny USBtinyISP AVR ISP Programmer Bootloader For Arduino IDE Meag2560 R3 With 10pin Programming Cable One - AliExpress
avr - I bought USB > FT232RL, can I use it to program a bootloader onto an Arduino? - Arduino Stack Exchange
Mini / Type-c / Micro Usb Nano 3.0 Controller, Compatible With The Bootloader, Nano Controller For Arduino Ch340 Usb Driver 16mhz Atmega328p - Temu Philippines
Arduino as ISP to Burn Bootloader on AVR Microcontroller - YouTube