{# scenario
variants -> similar variants by variant's category -> variants group by product's "device" category field
#}

{# Similar Variants with eager loading #}
{% set similarVariants = craft.commerce.variants({
	relatedTo: someElements,
	with: ['product.device', 'product.url']
}).find() %}
{% set similarVariantsByProduct = similarVariants | group('product.device | last ') %}
{% for productDevice, variants in similarVariantsByProductId %}
<a href="{{ variants[0].product.url }}">{{ productDevice }}</a>
{% endfor %}