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A bit out of date, but this interactive map of step free London is very good
All the London railway stations :
London Overground (North London line) between Stratford and Richmond.
I visited Hackney Wick in November 2021. It is not far from the Olympic Park , aka West Ham Football stadium. The step onto the trains is a very large step.
Hackney Wick station - in November 2021
Accessibility friendly : Partial.
General description : The station appears to be step-free to platforms from the entrance via lifts. See wiki
More comment : National Rail Map & Guide .