One method to secure your communications is:

1. On a crappy, or old phone, you install the SIM, or configure the e-SIM.

2. Use it as a hotspot

3. Use another phone (with no SIM or e-SIM) to connect to the crappy phone with SIM or e-SIM

4. Regular calls will go to the crappy phone, Telegram, Signal, WhatsApp calls will go to the no SIM phone.

Avoid installing apps like Instagram, Facebook, TikTok, WeChat, or other invasive apps on the no SIM phone.

I don't recommend iPhone devices, but you can De-Google an Android phone, or install Graphene OS or CalyxOS on some devices like Google Pixel, and other brands.

Voilà! You're set.