Hello Kristy,
Thank you for your post!
Unfortunately poly tubing fittings are very unlikely to be compatible with the PEX. Most brands will have a different inside diameter than the corresponding size of poly tubing. For example, a common inside diameter of 1/2" PEX tubing is 0.475", while a common inside diameter of 1/2" poly tubing is .600". The best bet would be to locate PEX specific fittings, they'll be designed to accommodate the inside diameter and (depending on fitting type) the thicker walls seen on PEX tubing.
With the correct fittings in between the end of the PEX and the beginning of the drip tubing you could use PEX, but I’m not sure that the cost of all the extra fittings and the time it would take to assemble them would be worth it. I have used a Sharkbite water faucet at the end of my PEX plumbing. They are push-to-fit and quick to install, but pricey.
Kristy Kittle