nothing wrong with Viber technically. If you’re lucky higher than 10 Android GSIs see attention, at least one user showed interest in Week 11. 2023: Development and Testing Updates - #4 by Lynix
If you elevate to adb root I’m think you can overwrite the ttf files and give it a go (no magisk needed, you can just extract the ttf and place them in /system/fonts/) - https://forum.xda-developers.com/t/magisk-module-emoji-sets-by-rkbdi.4120991/