The online store design is important for user experience and driving sales. It is quite essential to make sure that visitors find the product details on the web page easily.
Keeping this point in mind, I have come up with a solution to set image gallery Fotoroma thumbnail as vertical view in Magento 2.
By default, the image gallery Fotoroma thumbnail is set in horizontal view in Magento 2 as shown here:

However, some images may look better when shown in the vertical view. Or else, the vertical view may be more suitable based on your Magento 2 store theme.
Hence, you may want to change the image gallery Fotoroma thumbnail from horizontal view to vertical view in Magento 2 which can be done using the below method:
Method to Set Image Gallery Fotorama Thumbnail as Vertical View in Magento 2:
In the view.xml at app\design\frontend\Themes\Yourtheme\etc
Find the below line
<var name="navdir">horizontal</var>
Replace with below code:
<var name="navdir">vertical</var>
That’s it.
Once you implement the above code, the image gallery will be displayed as a vertical view like this:

Also, do share the post with Magento 2 store owners via social media to help them enhance the layout of the product page in their online store.
Thank you.