There needs to be the option to filter the Item Availability screens by Location and Item Variant. Yes it is possible to apply a flowfilter to the item list view and then open the Item availability screen to see filtered results however this present two usability issues:
1) There is no way of seeing a filter is applied.
2) You can't look (at for example The Item Availability by Variant) and then from within the screen apply a filter to see what the availability is for a particular warehouse.