I had a chorus of “who needs spares spokes” from riding buddies, the answer was with a niche hub set up I do.
Broke four spokes on the drive side hammering through a rock garden on a 6″ travel bike because fingers were to tired/sore to brake and just had to ride it out.
Would have screwed up the holiday if I hadn’t had the spares.
Others stuff
If you have a dropper post, take a spare standard one just in case.
Spare tyres and tubes or even a spare set of wheels with a different set of tyres.
Brake pads and bleed kit
A selection of nuts, bolts, chainring bolts etc.
Rear mech.
Some of the group took two bikes over, but we did drive over with vans.