Purely digital or hybrid analog digital silicon photomultipliers, based on CMOS SPAD photodetectors, have been developed for a range of high-energy and nuclear physics applications, including at EPFL's AQUA Lab in collaboration with external partners. The requirements can widely differ, such as high timing precision and detection at low event rates for time-of-flight PET (DIGILOG project), very high data rates, spatial granularity, and low light level operation in ring imaging Cherenkov counters (RICH) at colliders (spadRICH), or single-SPAD spatial granularity over large overall areas at low duty cycle when employed as active neutrino targets coupled to scintillating fibers (platonSPAD). Emphasis is often on high photon detection efficiency in the visible, coupled to tiling capabilities. Operation can likely take place at low or even cryogenic temperatures and/or high radiation levels.