SHT21 i2c sensor gives 'list index out of range'

The setups via the Linux host are always a bit fiddly. It usually has a lot of quirks, starting from the correct setup in the OS with its device tree overlays, through the userspace GPIO control libraries, up to Klipper.

I’d rather recommend using a small RP2040 board and hooking up your sensors there. Often, it’s a lot less problematic. For an example see Klipperize IFD-175 AP (prototype)