Are you serious here? Working in AdTech - which does (or at least should) translate to "working on undoing the good which used to be the public internet" - you most certainly realise, and possibly salivate over the breadth and width of Facebook's means to profile 'net users, whether those be actual Facebook (as in "Facebook the site, Instagram, WhatsApp and whatever other company they reeled in") users or otherwise. For those who want to keep their exposure to AdTech as small as possible it is adamant not to feed the beast if this can be avoided. That means not using any of their products and blocking access to any of their properties. It means not believing a word of what Facebook says about keeping WhatsApp apart from their other properties as they have shown time and again that they can not be trusted - something which is endemic when it concerns anything related to AdTech, probably because the lure of all that user data just waiting to be exploited is simply too big.
While this might not work as an argument to convince friends and family to stay away from Facebook (et al) it is the actual reason for doing so. It is just that the argument smacks too much of politics and zealotry to get people to change their ways.
To answer the original poster's question I'd suggest to simply use something else and give those friends and family your contact info on that other thing. There are plenty of options out there, all with their own pros and cons. The easiest sell will probably be Telegram since it offers a far superior user experience over WhatsApp, especially for those who use more than a single device. That this implies that Telegram stores user data and as such theoretically could do all sorts of nefarious things with it is just as interesting to the average user as the fact that Facebook will have been abusing WhatsApp data for years now, most people simply don't care. Telegram now also offers video calls by the way which takes away the last advantage WhatsApp had.