My DCs are motivated more by comfort than conformity.
DS1 is autistic with sensory issues so was grey shorts all year from y1 (when I gave up trying to battle with trousers, and school dropped seasonal and gender terminology from the uniform list) until y6. At some point I gave up buying stunt trousers as they were always passed to DS2 with tags. The advantage of shorts was that his legs dried quickly after walking to school, and the fabric isn't that warm on the shins of trousers anyway and especially not when flapping around wet. Also we could fit to waist and not worry about him looking like a mis-shapen sack of spuds in trousers bought for length with the waist yoinked in to the maximum.
Both DSs like long hair. This is an interesting social filter at identifying narrow-minded idiots.
DS1 did have cardigans in yR/ KS1 for the practical reason that he could take them on/off without risking injury to his ears and nose from the snug neck hole while wrestling them over his generous cranium. Cardigans are associated more as being feminine, but not exclusively so, and the sweatshirt style with large buttons was more neutral in style and not "feminised" with decorative trims. There have been phases of male cardigans coming in and out of fashion and they do have advantages of being easier to wear and more flexible for temperature control over a jumper. Visually the cardigan blended in with the sea of sweatshirts/ jumpers/ cardigans.
The gingham shorts are fine for girls who want to be active and are a halfway between traditional shorts and gingham dresses. While logically there should not be an issue with boys with wearing them too, the social reality is that boys will not be wearing items of that fabric, tend to feel well catered for in traditional shorts and they will stand out very obviously and there will be someone with something to say about it that is likely to result in upset.
My children have always abided by the uniform policy, but not in the most traditional conformist way. When they have ended up with stupid comments they've had the confidence to know that they were choices that they made from their own comfort and confidence. When they have wanted change we've discussed it and adapted (DS1 dropped both cardigans and sweatshirts and was happy with only polos and shorts)
Now DS2 is secondary age, he's seperating dressing for free choice at home, and dressing for expectations when out socially around peers which is a normal process to go through. DS1 DGAF!