I don't think there's any delegation services left for SPT - I might be wrong, to earn from that stake you have to upvote any content with the SPT tag, easiest way to do that is using the splintertalk.io frontend.
As far as I am aware SPT should be gaming content so with your stake you help by DVing the seveal abusers of the tag, I do this myself - nullifying the SPT rewards of people posting flower pictures, for example.
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