Adding a pullup resistor to 5V on the output will make the probabilities for success with 3.3V micro even greater (preferable on a 5V tolerant pin, but the protection will usual handle it).
No it won't, have you read the specification on how much current the ESD protection diodes can take?No nether have I , it is something the manufacturers do not specify. Only the most shoddy designer makes use of these.
The protection diodes can usually handle 10mA, it is in many chip datasheets.
You are totally missing the whole point here. We are trying to drive a WS2812 from a 3V3. We know that while it occasionally works it is outside the specifications
I'll defintiely need the 60 LED's / meter
Ifeel that 30 LED/ strip will be adequate.
Please point to a data sheet for a processors used on any Arduino that gives that figure.
And while you are at it, point us to a datasheet for any other processor that specifies 10 mA into the protection diodes.