Alternative to digitalPulse for remote control sockets?

Not yet - I'll try and have another look soon. I think the changes improved matters slightly but it still wasn't great. To do SPI, I'd do something like:

SPI1.setup({ mosi: output_pin, sck : pin_you_dont_use, bitrate: 125000 });
var data = new Uint8Array(18*24);
var n = 0;
function push(on, cnt) { while (cnt--) data[n++]=on?0xff:0; }
// now fill data with bytes - 0xFF for 1, 0x00 for 0
for (var i=24;i>=0;i--) {
    if ((bits>>i)&1) {
      push(1, 13);
      push(0, 5);
    } else {
      push(1, 5);
      push(0, 13);
    }
  }

SPI1.write(data);

Not tested, but that's the rough idea - create a big array with 0 for off, 0xFF (all 1s) for on - and transmit it. nRF52 should do that via DMA which will be nice and smooth