The Rolls-Royce SMR, also known as the UK SMR, is a small modular reactor (SMR) being developed by the Rolls-Royce (RR) company in the United Kingdom.
The company has been given financial support by the UK Government to develop its design. It is estimated that the 470 MWe units will cost around £1.8 billion once in full production, compared with £22 billion for a full-sized nuclear power station such as the planned 3,300 MWe Sizewell C. Construction time and site size needed will also be lower.
The nuclear reactor startup OKLO is working with Idaho National Lab to get its liquid metal-cooled fast reactor design (AURORA, 15MWe) up and running by 2027 which Open AI CEO Sam Altman intends to use for his company's power source. Details here.
They also have a different business model.