  A search for interactions from solar $^8$B neutrinos elastically scattering
off xenon nuclei using PandaX-4T commissioning data is reported. The energy
threshold of this search is further lowered compared with the previous search
for dark matter, with various techniques utilized to suppress the background
that emerges from data with the lowered threshold. A blind analysis is
performed on the data with an effective exposure of 0.48 tonne$\cdot$year, and
no significant excess of events is observed. Among results obtained using the
neutrino-nucleus coherent scattering, our results give the best constraint on
the solar $^8$B neutrino flux. We further provide a more stringent limit on the
cross section between dark matter and nucleon in the mass range from 3 to 9
GeV/c$^2$.
