A DIY USB-UART converter using a PIC16F1459 described in this blog post - https://snikolaj.github.io/electronics-projects/2022/10/11/diy-usb-uart.html
Schematic and final build included - requires a minimal amount of components and extra chips, TXB0108 could be replaced with a TXB0102.
Works at 3.3V and 5V, tested at 115200 baud but should work at up to 256000 baud.