Get whether some (but not all) of the variants products are out of stock

some_stock.liquid

{% assign some_stock = false %}
{% assign out_of_stock = 0 %}
{% for variant in product.variants %}
  {% if variant.available == false %}
    {% assign out_of_stock = out_of_stock | plus: 1 %}
  {% endif %}
{% endfor %}
{% if product.variants.size != out_of_stock and out_of_stock > 0 %}
  {% assign some_stock = true %}
{% endif %}