Hello Sebaz
Yes they need to do some edits to your theme code we were able to do our self for individual products, but we have some products with different color we wanted too show inventory individually inventory variants. We use code developer briskdeloders.com they will add the code for you and it’s very affordable price under hundred dollars, you can see it on our website we use the same theme.
https://mybellas.com/collections/area-rugs-1/products/madison-926-light-grey-blue
but if you want to show inventory of all variances combined for product
add this code to Snippets product.liquid
Underneath {% unless onboarding %}
<div id="variant-inventory">
{% assign total = 0 %}
{%for variant in product.variants %}
{% capture i %}{{ total | plus:variant.inventory_quantity }}{%endcapture%}
{% assign total = i %}
{%endfor%}
{% unless total == '0' %}
Only {{ total }} left
{% endunless %}
</div>
