Remember that any LOCALLY approved EV without a valid EU registration is not perse registerable in any other EU country,In The Netherlands you can only use EMC certified parts which do not exist for most components removed from wrecks. The UK does not have this restriction. I''m not sure about Germany.
Meaning getting your car approved in the UK or Germany doesnt help you when registering in NL. They simply wont approve it without an EMC document.
There is another way to do it in the NL when using donor-vehicle parts.