So to build a Web App on top of Shopify StoreFront API, we need to show filters at the sidebar.
Let's say a user navigates to a page which lists some products based on tag or collection. I assume it is a general and standard thing to present the user with some filters to filter down the list to what they want, right?
It is possible with Liquid files using Collection.tags documented here: https://help.shopify.com/en/themes/liquid/objects/collection#collection-tags
Reading the StoreFront API docs I don't seem to be able to find a way to do that.
Do Shopify provides or plans to provide that in the near future?
Definitely a reasonable request, and a shortcoming our storefront team is aware of.
I would feel relatively confident saying that it is probably something you'll end up seeing in the future, but to provide full disclosure it's also not something being actively worked on right now - so I wouldn't be able to provide any sort of a timeframe.