The prototype’s maiden flight had a tail-dragger undercarriage.
The ME262 jet engines like all jet engines today, required proper materials for the combustion chamber in particular and other parts like the compressor blades. These were metals in short supply and a tenuous supply was available from a neutral country which at any time may have withdrawn access. So the jet designers tried alternative combustion chamber materials. including some kind of insulating resins or pastes that could be applied to the inside of the chamber. These achieved limited success.