I’m an owner of a Orbiter 1.5 Extruder where there i discovered that an official filament sensor is available. Unfortunately it is a bit more tricky than with the Orbiter 2.0 Extruder. Originally i discovered the filament sensor on thingiverse and already was about to hit the slicer when i saw in one of the comments that the files are not the latest ones. These actually can be found on the page of the author - make sure to pick the latest files (currently version 2.2).
For the inner PCB and other accessories, i went on aliexpress and found the components immediately for sale* - just make sure to choose the version for the 1.5 orbiter.
One of the changes to the original design that i found very useful was the model to replace the lightguide by one with an M6 adapter to directly connect the PTFE tubes.
For the klipper configuration of the sensor it is best to look at the page of the author - he has described everything over there.