Electric motor wheel made of Rs 125 frame itself + registration ?

Moin, I’ve been asking myself the question for some time if it wouldn’t be possible to build an electric motor bike myself and register it? Given the rising petrol prices (the same €1.79 for 1 litre super), this idea is becoming more and more marked. I thought I’d take a frame, rim, etc. from an Rs 125 and build an e-motor with 21kw pure + batteries, so that I can drive it with the A limited. Would I be happy about the answers?