Will WhatsApp work with an eSIM?
Yes, with no changes: WhatsApp is tied to your number, and data can go through any line, the eSIM included.
Yes. WhatsApp, Telegram, Signal and Messenger are tied to your number and account, not to the SIM your data goes through. Your number stays on the main SIM and you use the eSIM for data on the trip; the apps don’t notice the difference. Your contacts, chats and groups stay as they are.
Voice and video calls in these apps work too, because they run over the internet. One exception: in the United Arab Emirates, operators block WhatsApp and FaceTime calls; people there use Botim or Zoom.