Naively, I moved my icons to (.png) to standard HTML emoji in order to make the pages lighter. The web pages are served by a small microcontroller - ESP32.
On most devices it works fine. But on others it happens some emoji are not rendered (blank square). I checked on some websites that list all the emojis, like this, and it confirms that some of them are not available.
In the specific case, also the most common one (grinning fade U+1F600) is not rendered.
I checked the customer's browser and it is Chrome v101 (april 22). I also checked the settings about the permissions to load fonts. By the way a Chrome v95 on Android render them correctly.
So the questions is: where are the emoji stored? Are they built-in in the browser?
Emojis are not typically "built-in" to browsers themselves, but rather rely on the fonts available in the operating system or provided by external resources. Different browsers and operating systems might have different levels of support for emojis, leading to variations in rendering.
If you're looking to ensure consistent emoji rendering across devices and browsers, you might consider using an external font that includes comprehensive emoji support. This can help mitigate the issues you're experiencing with missing or incorrectly rendered emojis.