I've been using this exact test for years now to judge a phone/tablet before buying/recommending - devices with the exact same SoC can differ wildly in performance.
Nowadays any phone that can't display 20k bunnies at 20FPS likely has:
1. An underpowered GPU.
2. Badly designed cooling.
3. A screen with a too high resolution.
Of course there are many more thorough and appropriate benchmarks, but this one doesn't require you to install anything and will give you an answer before you're approached by the store staff inquiring what is it that you're trying to do with the merchandise.
https://www.shadertoy.com/view/Xds3zN
Something with lots of work per pixel to complement Bunnymark's lots of pixels.
Given my aging Samsung Galaxy S6 averages about 30FPS for 20k bunnies in Firefox mobile, your criteria might actually be too lax...
Edit: And in Chrome on the same phone I'm in the mid 30's FPS for 50k bunnies.
To give an example: the Sony Xperia Z2 tablet appeared to be decent, because it had the - back then - state of the art Snapdragon 801 SoC.
I think I got less than 10k bunnies on it - no idea why(no power saving mode or anything), but it was a deal breaker for me.
(That’s not a statement on how impressive this is, just a “oh that’s how it’s done.”)
One thing that I didn't realize when I first saw it was that the demo is able to render so many sprites because it's doing the simplest possible thing - rendering just a few textures. If you render a bunch of different sprites with different textures, you'll get a big FPS hit.