How would one attach an optical fibre to a PCB for a display?
Fiber Optics, as a light source, and not a data transmission platform, is a "shoe-fits" type application. Fiber optic trees use heat shrink or electrical tape or tightly molded plastic as the method of optical coupling.


Data Transmission Optical Fiber Cable on the other hand, has closely designed standardized connectors, such as TOSLINK for consumer audio connections or SFP (small form-factor pluggable) connector used in some Cisco router Fiber Optic connections.

Using a 5mm or 3mm led with matching heat shrink tubing and enough fiber to fit is very very common in hobbyist modeling applications (which a well done scale model requires much of to look good (Model Enterprise Project)). If you need just a single thin strand, you could drill a hole in a led and hotglue the strand in (Model Train Project).

Fiber Optics are also used for Star Maps or Star Ceilings (The ends are mushroomed out using a lighter or other heat source, then hot glued in place).

Commercial applications use Light Pipes made of molded or extruded plastic, to channel a pcb mounted led (almost always smd) to an external case opening. I can't think of a single commercial/consumer/industrial product that would use fiber optic strands as internal light redirecting method, due to how unwieldily that would be in manufacturing, let alone technical support issues as connections are fragile due to the thinness.