Earlier quoted context omitted.
I used Signal and my main qualm with it is that messages don’t sync between platforms and also the phone app is nowhere as good as Telegram’s.
Well, if it would sync, it's not private. Unless the app allows you to sync the keys offline. Telegram doesn't sync either if you enable e2e encryption. But I agree that Telegram apps are great. Both Android ones, and the desktop ones as well. Small, fast, reliable, great UX.
And why wouldn't the app allow it?