PIR sensor that fits in a GU5.3/GU10 downlighter?

Random I know but more ‘specialist’ forums never seem to deliver the goods!

I want to convert my bathroom ceiling extractor fan from light switch activated to PIR activated.  Its got a defunct GU5.3 fitting in the fan itself so it would be very nice to add a PIR sensor in there rather than cut more holes in the ceiling.

Seen plenty of bulbs with an integral PIR sensor, but I don’t want a light, I just want an output to trigger the fan when someone steps in the shower rather than turn on for 30 minutes when someone goes for a 3am widdle.

Anyone know if this exists?  I’ve just spotted some miniature PIR sensors on Amazon so I can achieve what I want but would mean I need to start chopping and fabricating a mounting plate to adapt them to fit!  If such a thing exists I suspect either GU5.3 or GU10 would both fit.

Nothing to see here.

I have no advice except to say I fitted a humidstat to our bathrooms. No fan until the shower starts steaming. I suspect some members of the house have tried to set it off with a steaming pile, but no one has managed that yet…

Yeh I considered a humidistat but a standalone one is quite pricy and my ceiling vent is just an inlet, the fan is in the loft so that rules out an all in one unit.

I bought this in the end, hopefully it fits the job and as it’s small I’m hoping I can fit it quite high inside the bulb enclosure so it can only sense movement directly below, instead of trying to shade one side of the sensor and not get set off by steaming piles…

https://amzn.eu/d/fpmwFFc