Celebrim
Legend
There is a practical way, and that's for the DM to roll physical dice at home rather than rolling on roll20, for rolls the players aren't supposed to see.
That's how our DM does it, anyway.
I mostly play on Discord these days and when I want to conceal a roll I whisper to the dice bot and get a private reply. I'd be really surprised if there isn't a similar concept on Roll20.
But I also do have dice on my desk I can roll in a pinch or if it would be faster than sending a message to the dice app.