M.S.
We've done saline drops with our son since birth, starting with just a drop, not caring if it all got in his nose.
It started with him crying, then onto tolerating it, then onto thinking it was fun, and now on to demanding it, haha. We do it every morning/night. Unless he had a cold (he's had 2), then we did every diaper change and more if needed to keep the mucuous flowing out.
He definitely likes the mist better than the drops - maybe you could try that?
Good luck!!