Although, with the single seat deregulated models, all you need is a pilot's licence - so any need for conversion training there?
(it is possible to get a microlight licence without doing any dual training, as well!)
The single seat de-regulation is de-regulation with respect to certification and airworthiness requirements for the aircraft. The aircraft still needs to be registered and the pilot still needs an appropriate licence, medical etc
Yes it is possible still to obtain an NPPL with a microlight rating on it from scratch without doing any dual training. It is limited to single seat aircraft and I don't know of any instructors who do it........most prefer to teach you on a normal club aircraft and then once you qualify set you free on your single seat.
Of course you will still follow the required sylabus but it will all be supervised solo. Since the instructor is not there with you, it will be very gradual and slow progress and generally (as you would expect) takes more time than dual training.
Regards,
DFC