Dashboard Template filter -- get URL query string?

I’m using the auto entities card with the template filter, along with the template entity row custom card, to dynamically show some information on my dashboard. I would like to add some kind of filtering to this card, to select the type of entity rows that get displayed.

I think I could make it work with an input_select entity, but there are two issues with this: 1) the filter values have to be specified up front, and 2) all users of the dashboard have their values filtered the same way.

I thought I might be able to just add links with a query string to that dashboard page, however, I don’t see any way to get this value for use in the template. Is it possible to retrieve the query string (e.g. /lovelace/myview?category=value)? Or maybe there’s an alternate way to make this happen?

Here’s what I’d like to do, ideally (simplified code):

type: custom:auto-entities
  type: entities
  template: >
    {% set ns = namespace(results = []) %}

    {% set category = "value" // need:  something like request.querystring("category") %}

    {% for obj in
    state_attr("sensor.mysensor","details") |
    selectattr("category", "equalto", category) | list %}
      {% set ns.results = ns.results + [{
          "type": "custom:template-entity-row",
          "name": obj.name
    {% endfor %}

    {{ ns.results }}

Guess I’ll use input_select then. Bummer. Thanks anyway.