My experience so far has been that ws2812 leds can be driven directly by a 3.3V Arduino such as Wemos mini. I may well just have been lucky so far.
But with ws2811 chips and "clones" like GS1903/TM1903, when using a 3.3V Arduino, level converters have been needed.
I also found that the LLC modules designed for i2c bus lines worked with ws2811. However, the circuit was not very stable. Touching the LLC module with my fingers would cause the data signal to the led strip to be unreadable and the strip would start to flash and change colour randomly. Taking my finger away, everything started working normally again.
My theory as to why the LLC modules are unstable is that they don't switch fast enough. i2c signals switch at 100KHz, although they can also optionally be 400MHz on most Arduino. ws2811 signals switch at 400KHz and ws2812 at 800KHz.
With 74hc14 chip instead of the LLC, there was no instability. Touching the circuit did not affect the strip, which updated perfectly.