The 1.65V to 3.6V supply window means it works on a 1.8V core rail as easily as a 3.3V I/O rail, but note that at the lower end the 12 mA output drive is specified at the rated supply; actual drive current scales with VCC. If your design runs the buffer at 1.8V and expects full 12 mA into a heavy load, check the output I-V curves in the datasheet.
The ROHS3 status means it meets the current exemption limits for lead in solder and other restricted substances, so it clears EU and China regulatory checks without a waiver.