@Sebastiano To add to what @DavidCarlisle said, I would say don't comment on this at all. As David said earlier, the question wasn't that great to begin with, so if someone want to downvote it, they can. They even left a comment as to why, which means it wasn't an unmotivated vote. So learn from the experience and don't get into discussions with people about their votes.
@DavidCarlisle You would be surprised how many people ask for this, even in math mode (which I do not support). Any way, I love emoji not because I often use them, but because they enabled colored font formats which I have been longing for, and often cause many Unicode handling bugs to get prioritized and fixed.
@UlrikeFischer There are different formats used by different fonts, this is Noto Color Emoji which causes LuaTeX to not generate a PDF when used with luaotfload. May be you used Segoe UI Emoji which uses a different format (the same format as my colored Quran font). There is also Apple Color Emoji which uses a third format, it should work but I didn’t test it.
! error: (file /usr/share/fonts/noto/NotoColorEmoji.ttf) (ttf): sfnt table not
found
! ==> Fatal error occurred, no output PDF file produced!
The error does not say what table it is missing, but the font has no outlines only glyph bitmaps, so probably the font subsetting/embedding code does not like. The trick is to extract the bitmaps and use them as images, so the font does not needed to be embedded in the PDF file.
The font loader seems to have support for Apple Color Emoji which needs similar treatment, but it also requires external tools to convert the images to PDF (no idea why), my code doesn’t require any external tools.