So as we all know, WhatsApp is... pretty much unavoidable for day-to-day communications if you live outside the US. I have avoided it up until now, using solely Signal and Telegram (with e2ee secret chats), but now the pressure has finally caved in and I need WhatsApp working.
So I made a secondary user profile, installed Google Play Services, created a fresh Google account, downloaded WhatsApp and... it fails to send the SMS. Every time, no matter the number I put, it gives the error (roughly translated): "We are unable to deliver the message, please try again in 1 hour".
I tried downloading WA from APKMirror, with no luck (But then again APKMirror is just a reupload of google play so not sure what I was expecting). And the issue is definitely not with the SIM card or SMS receiving, other apps have verified just fine and I sent SMS to myself from a different phone number and they are received ok.
This is where I got out an old iPhone (to be precise, 2017 iPhone X), wiped it, made a fresh Apple ID, downloaded WhatsApp, and typed in the phone number. The SIM card was still in my Pixel, with GOS. And it worked, first try! The message delivered and I can use WhatsApp normally on the iPhone. But the issue is, I don't need it on my iPhone, as it has extremely short battery life. As a short term solution I could carry it around switched off, but Apple does invasive tracking so for long term I would rather have it in a sandboxed profile on the Pixel.
Phone verification also fails -- "We are unable to call you. Try again in 1 hour". Looking online for various solutions, I only found a strange post from 2012 on XDA that doesn't contain a solution. WhatsApp support team (via email) is no help either, they insist something is wrong with my SIM card.
Any ideas on how to solve this? Thanks in advance