The hard part is getting others to join. If all of your fam has iPhones and you are the one Android person, getting them all to join Signal just for you is a tall order.
Exactly, who is using bog-standard texts and phonecalls in this day and age? Do they also use internet explorer because that's the default too? Even if you're not on Signal, everyone and their mums has WhatsApp, I don't see how this is even an issue!