Amazon sells this, $32
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
As note, I have a compressor, so declined buying a special pump to inflate a mt bike tubeless. Cheaper to get the Amazon compressor inflator.
I have only been 50/50 on inflating a 2.4” mt bike tire with a floor pump, always needed my air compressor. Never tried CO2, I’ve heard that can work.