https://www.nature.com/articles/s41586-020-2550-z
[W]e showed that patients (n = 23) who recovered from SARS (the disease associated with SARS-CoV infection) possess long-lasting memory T cells that are reactive to the N protein of SARS-CoV 17 years after the outbreak of SARS in 2003; these T cells displayed robust cross-reactivity to the N protein of SARS-CoV-2.
I’m aware of the study. It was performed in a lab using samples taken from donors. It showed that there is a level of cross-reactivity. There is no data on this providing immunity in the real world. There have been no challenge studies, nor any epidemiological studies (with such a small sample size, this would be difficult anyway) to demonstrate whether any of this actually has any impact on SARS-CoV-2 infections.