As someone who has sought such a thing, I can at least give my personal experience:
Every single 5e DM I have ever asked for homebrew content has said no, unless they were already a close personal friend.
Literally 100% of 5e DMs I've asked, with one friend of mine as the only exception. Most of them complimented me on my design; most of them said that they thought it would probably work out alright, or didn't comment at all. All of them were quite polite about it.
Over a year of applying for 5e games, and none of them accepted.