Custom breadcrumb

Regarding your question, please follow this instruction, you are able to custom a breadcrumb by using Custom liquid

1. Within a product page in Customize panel, click Add section then select Custom liquid:

2. Drag the Custom liquid to the very first place, make it the first section:

3. Click on the Custom liquid, in its text field, paste the code below:

<div class="page-width"><h3 class="title"><a class="link link--underline" href="{{ routes.root_url }}">Home</a> / <a class="link link--underline" href="{{ product.collections[0].url }}">{{ product.collections[0].title }}</a> / {{ product.title }}</h3></div>

You may want to change the paddings to zero to reduce the spacing.

4. A simple breadcrumb should be displayed by now:

I hope this helps