Have Alexa TTS read an Item State

You might have to use a script to do it.
Example with JRuby (you’d need to install the jruby automation addon):

configuration: {}
triggers:
  - id: "1"
    configuration:
      itemName: BlueIris_Alarm_BlueIris_Alarm
    type: core.ItemStateUpdateTrigger
conditions: []
actions:
  - inputs: {}
    id: "2"
    configuration:
      type: application/x-ruby
      script: Evelins_Echo_Dot_Speak.command(event.state)
    type: script.ScriptAction

PS You should format yaml / other code using code fences when posting it on this forum, to preserve their indentation and special characters.

It will still work, with the number converted to string automatically. If you want to format it a certain way, e.g. to specify a fixed number of decimals, you can do that too, e.g.

Evelins_Echo_Dot_Speak.command(event.state) # Works for numeric states too

Evelins_Echo_Dot_Speak.command(event.state.format("%.2f")) # This ensures 2 decimal points