I definitely don’t recommend WD40. It’s a Water Dispersant/Solvent not a lubricant. Even their lubricant (as labeled) isn’t very good.
A good, standard, petroleum grease is ok or a lithium based lubricant is better.
The shock bushings have a plastic keeper ring holding the sleeve in and you can pop that off with a flat screwdriver and slide the bushing sleeve out to lubricate it. The suspension arms have metal caps and sleeves inside a plastic bushing. They shouldn’t require lubrication. The plastic used in the bushing is essentially self-lubricating. However, when the bushing gets worn out, it can cause the end caps to rub on the eye of the arm and cause squeaking. In which case the bushing needs replaced. On a new machine, where the bushings can’t reasonably be worn out, I’d check that the bolts are fully torqued down. There shouldn’t be any rotation of the end caps, bolt or bolt sleeve, so all the wear is on the plastic bushing.
Also. The a-arm end caps have an o-ring and the shocks have a seal, so any spray lubricants aren’t likely to get in to the parts that would need lubricated.