How to place an update available icon on the dashboard?

Configuration Frontend
1

I would like to see a conditional card on the dashboard telling me whether there are any updates available for anything I can do this for each device individually plus the HA core, OS, etc. but I’d like one card for all.

2

How would you want it displayed? You can have a list using the custom auto-entities card, a number using a template sensor, a binary sensor for on/off (also possible with template sensors). Do you want really all, or list specific ones? Then a group would do.

3

Just a binary sensor telling me there are updates available would do

4

Create a group and add all entities starting with “update.” that you want. The state of the group will be on if any of the entities turns on due to an update.

5

…which should be updated automatically when a new custom plugin / custom card is added / removed.

6

Since you know that it could be a template binary sensor - define it’s state (enumerate and check all “update” entities), then show this binary sensor as you like (Entity card, Tile card, …).

7

Here’s a template sensor I use that is true if any update sensor is true:

- binary_sensor:
  - name: Main Updates Available
    state: >-
      {{ (states.update |
          selectattr('state', 'eq', 'on') |
          list |
          count) > 0 }}

From there you could use the conditional disability on something like a tile card so that it shows only when there are updates available.