I'm stubborn. I say Signal is the only way to reach me. It surprises me how many people actually install Signal just for you when you tell them that. Family and friends is easy because if it's the only way to reach you, they'll install it. For others, I'm a bit machiavellian and tell them things like my phone is too old to install Whatsapp (was true with one of my phones). Or if they call︀ or SMS me, I'll wait a week and say "sorry I missed your text, I︁ never check it, but reach me on Signal and I check that all the time".︂ You can use this trick on Whatsappers too. Just ignore them for a week and︃ tell them you never check it, so they should install Signal to reach you instantly.︄
Lol. I'll do 27 card readers if I have︅ to! But some apps let you use open source authenticators like Aegis which doesn't spy︆ on you. Maybe some of your banks will let you. Even SMS is better 2FA︇ than bank's bespoke apps. See which ones give you options. I let them send SMS︈ to a number I switch on only for 2FA.
Privacy is never perfect but you︉ can reduce invasion of privcy if you're stubborn with them. One work client wanted me︊ to use some authenticator called Duo. I looked it up and it was as hellish︋ a privacy invasion as you'd expect. I told them I don't use a smartphone, so︌ they let me use SMS. Stubbornness works.