It is currently to use WhatsApp on Android 2.3.6 (Gingerbread).
Official support for WhatsApp on Android 2.3.6 (Gingerbread) February 1, 2020 android 2.3 6 whatsapp download
Using "modded" versions of WhatsApp (like WhatsApp Plus or GBWhatsApp) violates the Terms of Service and can lead to a permanent ban of your phone number. It is currently to use WhatsApp on Android 2
Telegram is generally more lenient with older hardware, though even they have raised their minimum requirements recently. android 2.3 6 whatsapp download