It might be good to try to match the same services and characteristics they're using for their sensor, to get a Puck acting like a Thingy:52 as far as their official App is concerned.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Mmm.. it's like a Puck, but huge and ugly.
They've posted some Node.js code to operate with the default firmware: https://github.com/NordicSemiconductor/Nordic-Thingy52-Nodejs/blob/master/lib/thingy.js
It might be good to try to match the same services and characteristics they're using for their sensor, to get a Puck acting like a Thingy:52 as far as their official App is concerned.