How to change number formats (decimals + thousand separator) for custom cards the right way?

While internal HA cards support local settings and especially number formats the custom cards seem to ignore the whole issue in general.

How can I make sure that i can use my local number format or to define such number format cause I simply do not longer wanna see “#,##0.0” format that do not make any sense and will only create confusion about the value.

1.846 kcal is quite the opposite of 1,846 kcal and there must be a way to make sure that it works like it works for all the internal cards.

Do not get me wrong: i am willing to add for each card a header just to make sure that I will get my domestic “#.##0,00” number format.
Of cause it would be nice if bar card would have a setup or definition where I can chose what I want, but even without that I can live if I will have at least a way to get my “#.##0,00” number format.

thx

Share your projects is not the place for this.

The custom card needs to support it. My custom weather card does this and uses the browser language to set the displayed data so maybe ask the custom card developer. It’s a simple change in the js.