Past experience have made me realize I really should be strict in breadboarding components first before immediately jumping into soldering them onto some protoboards.

So here it is: the Honeywell PMS and an Espruino MDBT42Q breakout, together with a lipo battery and a boost converter.

The test code was easy and simple as well (copied almost verbatim from the Espruino UART docs):

var s = new Serial();
s.setup(9600,{rx: D14, tx: D15});
s.on('data', function (data) {
  print("<Serial> "+data);
});

 Data sheet of the PM sensor is here: https://sensing.honeywell.com/honeywell-sensing-particulate-hpm-series-datasheet-32322550.pdf