It's worth noting that neither the demonstrator nor the Overture aircraft will utilise 'low boom' technologies currently being researched by NASA through their X59 program. Overture will be a 'traditonal' SST in the sense that it will boom.
The company originally aimed for M2+ but derated the performance requirement to M1.7 around 18-months or so ago. About the same time that Rolls Royce pulled out of their agreement with Boom as the engine development partner. It's hoped to eradicate some of the handling foibles associated with Concorde to allow the aircraft to be operated and managed in much the same way as any other airliner.