I got plenty of gripes with Signal (acting like a de facto proprietary app, backing up horrendously difficult, gimping the Android options in order to get to “feature parity” with the less developed iOS app, serious UI/UX missteps - the bubbles colouring debacle, no AMOLED mode etc.). Having said that, I let everybody know it IS my main messaging app - if they want to reach me, that’s where I’ll be. I do still use WhatsApp (barf!) and Slack, but exclusively for work-related stuff and I force close them the minute I walk out the office (if something blows up, a good, old-fashioned call will do). People who really want to keep in touch will eventually use an encrypted app, even if begrudgingly.
I also live in a country where WhatsApp is the messaging app almost everybody uses. You won’t be able to get all of your relatives, friends and co-workers on Signal, so I’d suggest you start small - get SOME people onboard, make it very clear you’re gonna be using WhatsApp for work-related stuff only, see what happens. Besides, Signal has its quirks, too - switching phones and backing up will lead to a lot of frustration and its devs proudly state that “more options is never the answer”. It’ll sadly remain a niche app for activists and the privacy-inclined, I fear. But if you really care about privacy, you should ditch Telegram ASAP.