No, if you add an entry to manual_value, it will just replace the looked up value with a static one. Maybe naming this field static_value would convey this better?
You can get the all-time count by adding the all-time period selector to the dropdown:

It’s just a simple change in the settings file of the component. I pushed a branch with this here: GitHub - nolosb/discourse-stat-banner at count. However, for a PR it would probably still need some logic to rename that variable on the dropdown?