Even if it was accurate matching Germany GDP when there's a war on their doorstep and being so heavily reliant on imported energy from Russia is hardly a reason to gloat.
If you track accurate up to date output from before the UK voted Brexit to the latest release and factor sterling devaluation then UK output is 70% the size of Germany, it was 90% before Brexit. Thats a £700 billion spread on output. For Wales particularly there is no economic upside leaving the EU, none whatsoever, only downside, it's just made us even more heavily reliant on block grant trickle down from a central source that is struggling to retain fiscal solvency.