There's no way to tell how many points an individual card is worth on the workboard UI right now.
If ManiphestTaskPoints::getIsEnabled() is set, the card should show this in the UI somehow.
(Note that 0 is a valid number of points, and distinct from null, which means "no point value assigned". We might want to show some indicator for that, but the lack of a point value might be good enough.)
Just rendering this on the cards should be good enough, all the JS should already deal with updates/etc properly.