Custom or stronger tile background colours

I’m building a screen for my elderly mother on a Guition ESP32-4848S040C_I (480×480, 3×3 grid). It has a 1×2 HELP tile that sends a critical alert to my phone. The red pastel background (#FADADD) is too soft for an emergency button; it should stand out instantly.

Request: let users pick their own tile background colour (a colour picker or hex value), or add a set of strong colours next to the pastels. The strong KEY_SWATCHES already used for alert buttons (e.g. red #D93A30 with white text) would be perfect for tiles too, including white text for contrast.

I checked whether Override YAML could do it, but the palette is compiled into theme.h, so it isn’t configurable today.