> The key was being stubborn and banking on them eventually wanting to talk to me.

This. Same for me. I just put a message like this in the family whatsapp groups and then deleted the app/account: 'Hey everyone, I'm not going to be on WhatsApp anymore - you can call, text, signal, telegram or email me. Talk to you later!'. It was that simple. It took a little while but now my family is on Telegram. I know they still use WhatsApp but it's honestly not my problem or issue that they use the app - I just don't want to.