while I welcome Emails, I also get hundreds per day, so if you are asking for help/time from me, please read, or at least skim through: Asking Smart Questions.
You shouldn't expect me to spend more time answering than it took you to ask the question with not enough details :)

Also, please understand that I just don't have time to give 1-1 help with individual projects, although I will do my best to help if you find problems with something I wrote/shared and you have suggestions, fixes, or a clear question which includes what you did already, what didn't work, and anything you can include to help.
When I write careful Emails asking for help from others, listing everything I've tried and what didn't work, I ended up fixing more of 50% of my problems before hitting the 'send' button :)

If you need help with:

• Btrfs, please post on the btrfs mailing list
• FastLED anything, use the reddit, you can ping me with /u/marcmerlin in your post if this is related to my code
• SmartMatrix anything, https://community.pixelmatix.com/, you can ping me by name in your post
• A github library I wrote: please open an issue so that your question and my answer are indexed and visible by others (of course, that means you also did a google search for your question too :) ).