I don't think the blog post itself is using that emoji font. The screenshot on the Noto Emoji Github page[0] doesn't look like it's using any gradients for the heart emoji, just flat shading. But it is using gradients for some of the other emojis (e.g. the croissant), and obviously the SVG fallback is all or nothing, not per-glyph.
alt Hacker News
I don't think the blog post itself is using that emoji font. The screenshot on the Noto Emoji Github page[0] doesn't look like it's using any gradients for the heart emoji, just flat shading. But it is using gradients for some of the other emojis (e.g. the croissant), and obviously the SVG fallback is all or nothing, not per-glyph.
[0] https://github.com/googlefonts/noto-emoji