I have hands on experience on uikit and jQuery. My client wants the look and feel of uikit and what do you suggest how to implement the same using theme module in outsystems, should I go for blank application, write all widgets on my own ? like, layout, popup, etc., ?


Well, yes, but I strongly suggest to use vanilla-theme of silkUI and work from there.

unless you are 100% sure, there is no pattern from uikit similar in silkUI.