How to flash ESPHome onto a WLED pre-flashed LS4P LED strip controller

I bought a LS4P-WLED and would like to flash ESPHome onto it. I assume that should be possible because there is also the LS4P-ESP version with ESPHome pre-flashed.

Would that be possible with a USB-to-Serial converter?

It's there an easier way?

I'm using Home Assistant, if that makes any difference.