Are instrument lights required for night VFR flight in an SLSA?
Cockpit lighting is not required to be present as required Night VFR equipment under Part 91 general flight rules.  That being said, there is the following Part 23 Certification Requirement for external and cockpit lighting.

§23.2530 External and cockpit lighting.
(a) The applicant must design and install all lights to minimize any adverse effects on the performance of flightcrew duties.

Under the terms of this regulation one could make the argument that an OEM applying for a normal category type certificate will need some type of effective cockpit illumination to minimize adverse effects on aircrews.